Getting started with implementing an explicit AI, based on the Essentials one.

Plugins/PkmnLib.Plugin.Gen7.Tests/DataTests/MoveDataTests.cs

@@ -1,6 +1,7 @@
 using System.Buffers;
 using System.Text.Json;
 using PkmnLib.Dynamic.Libraries;
+using PkmnLib.Dynamic.Plugins;
 using PkmnLib.Dynamic.ScriptHandling;
 using PkmnLib.Dynamic.ScriptHandling.Registry;
 using PkmnLib.Static.Moves;

Plugins/PkmnLib.Plugin.Gen7/AI/AIHelperFunctions.cs

@@ -0,0 +1,337 @@
+using PkmnLib.Dynamic.AI.Explicit;
+using PkmnLib.Plugin.Gen7.Libraries.Battling;
+using PkmnLib.Plugin.Gen7.Scripts.Side;
+using PkmnLib.Static.Moves;
+
+namespace PkmnLib.Plugin.Gen7.AI;
+
+public static class AIHelperFunctions
+{
+    public static int GetScoreForTargetStatRaise(int score, AIMoveState move, IPokemon target,
+        StatisticSet<sbyte> statChanges, bool fixedChange = false, bool ignoreContrary = false)
+    {
+        var wholeEffect = move.Move.Category != MoveCategory.Status;
+
+        var desireMult = 1;
+        if (move.User.BattleData?.SideIndex != target.BattleData?.SideIndex)
+            desireMult = -1;
+
+        if (!ignoreContrary && !fixedChange && target.ActiveAbility?.Name == "contrary")
+        {
+            if (desireMult > 0 && wholeEffect)
+            {
+                return ExplicitAI.MoveUselessScore;
+            }
+            return GetScoreForTargetStatDrop(move, target, statChanges, fixedChange, true);
+        }
+
+        var addEffect = move.GetScoreChangeForAdditionalEffect(target);
+        if (addEffect == -999)
+        {
+            return score;
+        }
+        var expectedEndOfTurnDamage = 0;
+        target.RunScriptHook<IAIInfoScriptExpectedEndOfTurnDamage>(x =>
+            x.ExpectedEndOfTurnDamage(target, ref expectedEndOfTurnDamage));
+        // If the target is expected to faint from the end of turn damage, we don't want to
+        // apply the score for the stat raise, as it will not be able to use it.
+        if (expectedEndOfTurnDamage >= target.CurrentHealth)
+            return wholeEffect ? ExplicitAI.MoveUselessScore : score;
+
+        if (!move.User.HasMoveWithEffect("power_trip"))
+        {
+            var foeIsAware = target.BattleData?.BattleSide.Pokemon.Any(x => x?.ActiveAbility?.Name == "unaware") !=
+                             true;
+            if (!foeIsAware)
+            {
+                return wholeEffect ? ExplicitAI.MoveUselessScore : score;
+            }
+        }
+        var realStatChanges = new StatBoostStatisticSet();
+        foreach (var (stat, i) in statChanges)
+        {
+            var increment = i;
+            if (!IsStatRaiseWorthwhile(target, stat, increment, fixedChange))
+            {
+                continue;
+            }
+            if (!fixedChange && target.ActiveAbility?.Name == "simple")
+            {
+                increment *= 2;
+            }
+            increment = (sbyte)Math.Max(increment,
+                StatBoostStatisticSet.MaxStatBoost - target.StatBoost.GetStatistic(stat));
+            realStatChanges.SetStatistic(stat, increment);
+        }
+        if (realStatChanges.IsEmpty)
+        {
+            return wholeEffect ? ExplicitAI.MoveUselessScore : score;
+        }
+
+        score += addEffect;
+        score = GetTargetStatRaiseScoreGeneric(score, target, realStatChanges, move, desireMult);
+
+        foreach (var realStatChange in realStatChanges.Where(x => x.value > 0))
+        {
+            GetTargetStatRaiseScoreOne(ref score, target, realStatChange.statistic, realStatChange.value, move,
+                desireMult);
+        }
+        return score;
+    }
+
+    public static int GetScoreForTargetStatDrop(AIMoveState move, IPokemon target, StatisticSet<sbyte> statChanges,
+        bool fixedChange = false, bool ignoreContrary = false) =>
+        throw new NotImplementedException("This method is not implemented");
+
+    /// <summary>
+    /// Checks if a stat raise is worthwhile for the given Pokémon and stat.
+    /// </summary>
+    private static bool IsStatRaiseWorthwhile(IPokemon pokemon, Statistic stat, sbyte amount, bool fixedChange = false)
+    {
+        if (!fixedChange && pokemon.StatBoost.GetStatistic(stat) == StatBoostStatisticSet.MaxStatBoost)
+            return false;
+        if (!pokemon.HasMoveWithEffect("power_trip", "baton_pass"))
+            return true;
+
+        switch (stat)
+        {
+            case Statistic.Attack:
+            {
+                if (!pokemon.Moves.WhereNotNull().Any(x => x.MoveData.Category == MoveCategory.Physical &&
+                                                           x.MoveData.SecondaryEffect?.Name != "foul_play"))
+                {
+                    return false;
+                }
+                break;
+            }
+            case Statistic.Defense:
+            {
+                var opponentSide = pokemon.BattleData!.Battle.Sides.First(x => x != pokemon.BattleData.BattleSide);
+                return opponentSide.Pokemon.WhereNotNull().Any(x => x.Moves.WhereNotNull().Any(y =>
+                    y.MoveData.Category == MoveCategory.Physical || y.MoveData.SecondaryEffect?.Name == "psyshock"));
+            }
+            case Statistic.SpecialAttack:
+            {
+                if (pokemon.Moves.WhereNotNull().All(x => x.MoveData.Category != MoveCategory.Special))
+                {
+                    return false;
+                }
+                break;
+            }
+            case Statistic.SpecialDefense:
+            {
+                var opponentSide = pokemon.BattleData!.Battle.Sides.First(x => x != pokemon.BattleData.BattleSide);
+                return opponentSide.Pokemon.WhereNotNull().Any(x => x.Moves.WhereNotNull().Any(y =>
+                    y.MoveData.Category == MoveCategory.Special && y.MoveData.SecondaryEffect?.Name != "psyshock"));
+            }
+            case Statistic.Speed:
+            {
+                if (!pokemon.HasMoveWithEffect("electro_ball", "power_trip"))
+                {
+                    var targetSpeed = pokemon.BoostedStats.Speed;
+                    var opponentSide = pokemon.BattleData!.Battle.Sides.First(x => x != pokemon.BattleData.BattleSide);
+                    var meaningful = opponentSide.Pokemon.WhereNotNull().Select(opponent => opponent.BoostedStats.Speed)
+                        .Any(foeSpeed => targetSpeed < foeSpeed && targetSpeed * 2.5 > foeSpeed);
+                    if (!meaningful)
+                        return false;
+                }
+                break;
+            }
+            case Statistic.Accuracy:
+            {
+                var minAccuracy = pokemon.Moves.WhereNotNull().Min(x => x.MoveData.Accuracy);
+                if (minAccuracy >= 90 && pokemon.StatBoost.Accuracy >= 0)
+                {
+                    var meaningful = false;
+                    var opponentSide = pokemon.BattleData!.Battle.Sides.First(x => x != pokemon.BattleData.BattleSide);
+                    if (opponentSide.Pokemon.WhereNotNull().Any(x => x.StatBoost.Evasion > 0))
+                    {
+                        meaningful = true;
+                    }
+                    if (!meaningful)
+                        return false;
+                }
+                break;
+            }
+        }
+        return true;
+    }
+
+    private static void GetTargetStatRaiseScoreOne(ref int score, IPokemon target, Statistic stat, sbyte increment,
+        AIMoveState move, float desireMult = 1)
+    {
+        var oldStage = target.StatBoost.GetStatistic(stat);
+        var newStage = (sbyte)(oldStage + increment);
+        var incMult = Gen7BattleStatCalculator.GetStatBoostModifier(Math.Min(newStage, (sbyte)6)) /
+                      Gen7BattleStatCalculator.GetStatBoostModifier(oldStage);
+        var actualIncrement = incMult;
+        incMult -= 1;
+        incMult *= desireMult;
+        var opponentSide = target.BattleData!.Battle.Sides.First(x => x != target.BattleData.BattleSide);
+
+        switch (stat)
+        {
+            case Statistic.Attack:
+            {
+                if (oldStage >= 2 && increment == 1)
+                    score -= (int)(10 * (target.Opposes(move.User) ? 1 : desireMult));
+                else
+                {
+                    var hasSpecialMoves = target.Moves.WhereNotNull()
+                        .Any(x => x.MoveData.Category == MoveCategory.Special);
+                    var inc = hasSpecialMoves ? 8 : 12;
+                    score += (int)(inc * incMult);
+                }
+                break;
+            }
+            case Statistic.Defense:
+            {
+                if (oldStage >= 2 && increment == 1)
+                    score -= (int)(10 * (target.Opposes(move.User) ? 1 : desireMult));
+                else
+                    score += (int)(10 * incMult);
+                break;
+            }
+            case Statistic.SpecialAttack:
+            {
+                if (oldStage >= 2 && increment == 1)
+                    score -= (int)(10 * (target.Opposes(move.User) ? 1 : desireMult));
+                else
+                {
+                    var hasPhysicalMoves = target.Moves.WhereNotNull().Any(x =>
+                        x.MoveData.Category == MoveCategory.Physical &&
+                        x.MoveData.SecondaryEffect?.Name != "foul_play");
+                    var inc = hasPhysicalMoves ? 8 : 12;
+                    score += (int)(inc * incMult);
+                }
+                break;
+            }
+            case Statistic.SpecialDefense:
+            {
+                if (oldStage >= 2 && increment == 1)
+                    score -= (int)(10 * (target.Opposes(move.User) ? 1 : desireMult));
+                else
+                    score += (int)(10 * incMult);
+                break;
+            }
+            case Statistic.Speed:
+            {
+                var targetSpeed = target.BoostedStats.Speed;
+                foreach (var opponent in opponentSide.Pokemon.WhereNotNull())
+                {
+                    var foeSpeed = opponent.BoostedStats.Speed;
+                    if (foeSpeed <= targetSpeed)
+                        continue;
+                    if (foeSpeed > targetSpeed * 2.5)
+                        continue;
+                    if (targetSpeed * actualIncrement > foeSpeed)
+                        score += (int)(15 * incMult);
+                    else
+                        score += (int)(8 * incMult);
+                }
+                if (target.HasMoveWithEffect("electro_ball", "power_trip"))
+                {
+                    score += (int)(5 * incMult);
+                }
+                if (opponentSide.Pokemon.WhereNotNull().Any(x => x.HasMoveWithEffect("gyro_ball")))
+                {
+                    score -= (int)(5 * incMult);
+                }
+                if (target.ActiveAbility?.Name == "speed_boost")
+                {
+                    score -= (int)(15 * (target.Opposes(move.User) ? 1 : desireMult));
+                }
+                break;
+            }
+            case Statistic.Accuracy:
+            {
+                if (oldStage >= 2 && increment == 1)
+                {
+                    score -= (int)(10 * (target.Opposes(move.User) ? 1 : desireMult));
+                }
+                else
+                {
+                    var minAccuracy = target.Moves.WhereNotNull().Min(x => x.MoveData.Accuracy);
+                    var previousMinAccuracy =
+                        minAccuracy * Gen7BattleStatCalculator.GetAccuracyEvasionStatModifier(0, oldStage);
+                    if (previousMinAccuracy < 90)
+                    {
+                        score += (int)(10 * incMult);
+                    }
+                }
+                break;
+            }
+            case Statistic.Evasion:
+            {
+                foreach (var opponent in opponentSide.Pokemon.WhereNotNull())
+                {
+                    var endOfTurnDamage = 0;
+                    opponent.RunScriptHook<IAIInfoScriptExpectedEndOfTurnDamage>(x =>
+                        x.ExpectedEndOfTurnDamage(opponent, ref endOfTurnDamage));
+                    if (endOfTurnDamage > 0)
+                        score += (int)(5 * incMult);
+                }
+                if (oldStage >= 2 && increment == 1)
+                {
+                    score -= (int)(10 * (target.Opposes(move.User) ? 1 : desireMult));
+                }
+                else
+                {
+                    score += (int)(10 * incMult);
+                }
+                break;
+            }
+        }
+        if (target.HasMoveWithEffect("power_trip"))
+        {
+            score += (int)(5 * increment * desireMult);
+        }
+        if (opponentSide.Pokemon.WhereNotNull().Any(x => x.HasMoveWithEffect("punishment")))
+        {
+            score -= (int)(5 * increment * desireMult);
+        }
+    }
+
+    /// <summary>
+    /// Calculates the score for the generic concept of raising a target's stats.
+    /// </summary>
+    private static int GetTargetStatRaiseScoreGeneric(int score, IPokemon target, StatisticSet<sbyte> statChanges,
+        AIMoveState move, float desireMult = 1)
+    {
+        var totalIncrement = statChanges.Sum(x => x.value);
+        var turns = target.BattleData!.Battle.CurrentTurnNumber - target.BattleData!.SwitchInTurn;
+        if (turns < 2 && move.Move.Category == MoveCategory.Status)
+            score += (int)(totalIncrement * desireMult * 5);
+
+        score +=
+            (int)(totalIncrement * desireMult * ((100 * (target.CurrentHealth / (float)target.MaxHealth) - 50) / 8));
+        return score;
+    }
+
+    private static int GetScoreChangeForAdditionalEffect(this AIMoveState move, IPokemon? target)
+    {
+        if (move.Move.SecondaryEffect is null)
+            return 0;
+        if (move.User.ActiveAbility?.Name == "sheer_force")
+            return -999;
+        if (target is not null && target.BattleData?.Position != move.User.BattleData?.Position &&
+            target.ActiveAbility?.Name == "shield_dust")
+            return -999;
+
+        if ((move.Move.SecondaryEffect.Chance < 100 && move.User.ActiveAbility?.Name == "serene_grace") ||
+            move.User.BattleData?.BattleSide.VolatileScripts.Contains<RainbowEffect>() == true)
+        {
+            return 5;
+        }
+        return 0;
+    }
+
+    private static bool HasMoveWithEffect(this IPokemon pokemon, params StringKey[] effect)
+    {
+        return pokemon.Moves.WhereNotNull().Any(move => move.MoveData.SecondaryEffect?.Name is not null &&
+                                                        effect.Contains(move.MoveData.SecondaryEffect.Name));
+    }
+
+    private static bool Opposes(this IPokemon pokemon, IPokemon target) =>
+        pokemon.BattleData?.BattleSide != target.BattleData?.BattleSide;
+}

Plugins/PkmnLib.Plugin.Gen7/AI/AIMoveScoreFunctionAttribute.cs

@@ -0,0 +1,8 @@
+using JetBrains.Annotations;
+
+namespace PkmnLib.Plugin.Gen7.AI;
+
+[AttributeUsage(AttributeTargets.Method), MeansImplicitUse]
+public class AIMoveScoreFunctionAttribute : Attribute
+{
+}

Plugins/PkmnLib.Plugin.Gen7/AI/ExplicitAIFunctions.cs

@@ -0,0 +1,70 @@
+using System.Linq.Expressions;
+using System.Reflection;
+using PkmnLib.Dynamic.AI.Explicit;
+using PkmnLib.Plugin.Gen7.Scripts.Moves;
+using PkmnLib.Plugin.Gen7.Scripts.Pokemon;
+using PkmnLib.Static.Moves;
+
+namespace PkmnLib.Plugin.Gen7.AI;
+
+public static class ExplicitAIFunctions
+{
+    public static void RegisterAIFunctions(ExplicitAIHandlers handlers)
+    {
+        var baseType = typeof(Script);
+        foreach (var type in typeof(ExplicitAIFunctions).Assembly.GetTypes().Where(t => baseType.IsAssignableFrom(t)))
+        {
+            var attribute = type.GetCustomAttribute<ScriptAttribute>();
+            if (attribute == null)
+                continue;
+
+            if (attribute.Category == ScriptCategory.Move)
+            {
+                // Check if the move type has a static function in the following format:
+                // public static void AIMoveEffectScore(MoveOption option, ref int score);
+                var method = type.GetMethods(BindingFlags.Public | BindingFlags.Static).FirstOrDefault(m =>
+                    m.GetCustomAttribute<AIMoveScoreFunctionAttribute>() != null && m.ReturnType == typeof(void) &&
+                    m.GetParameters().Length == 2 && m.GetParameters()[0].ParameterType == typeof(MoveOption) &&
+                    m.GetParameters()[1].ParameterType == typeof(int).MakeByRefType());
+                if (method != null)
+                {
+                    var optionParam = Expression.Parameter(typeof(MoveOption), "option");
+                    var scoreParam = Expression.Parameter(typeof(int).MakeByRefType(), "score");
+                    var functionExpression = Expression.Lambda<AIScoreMoveHandler>(
+                        Expression.Call(null, method, optionParam, scoreParam), optionParam, scoreParam).Compile();
+                    handlers.MoveEffectScore.Add(attribute.Name, functionExpression);
+                }
+            }
+        }
+
+        handlers.GeneralMoveAgainstTargetScore.Add("predicated_damage", PredictedDamageScore);
+    }
+
+    private static void PredictedDamageScore(MoveOption option, ref int score)
+    {
+        var target = option.Target;
+        if (target == null)
+            return;
+        if (option.Move.Move.Category == MoveCategory.Status)
+            return;
+        var damage = option.EstimatedDamage;
+        if (target.Volatile.TryGet<SubstituteEffect>(out var substitute))
+        {
+            var health = substitute.Health;
+            score += (int)Math.Min(15.0f * damage / health, 20);
+            return;
+        }
+
+        score += (int)Math.Min(15.0f * damage / target.CurrentHealth, 30);
+
+        if (damage > target.CurrentHealth * 1.1f)
+        {
+            score += 10;
+            if ((option.Move.Move.HasFlag("multi_hit") && target.CurrentHealth == target.MaxHealth &&
+                 target.ActiveAbility?.Name == "sturdy") || target.HasHeldItem("focus_sash"))
+            {
+                score += 8;
+            }
+        }
+    }
+}

Plugins/PkmnLib.Plugin.Gen7/Data/Moves.jsonc

@@ -438,7 +438,8 @@
       "flags": [
         "contact",
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"
@@ -704,7 +705,8 @@
       "flags": [
         "protect",
         "mirror",
-        "ballistics"
+        "ballistics",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"
@@ -770,7 +772,8 @@
       "category": "physical",
       "flags": [
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "beat_up"
@@ -1101,7 +1104,8 @@
       "category": "physical",
       "flags": [
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"
@@ -1413,7 +1417,8 @@
       "flags": [
         "protect",
         "mirror",
-        "ballistics"
+        "ballistics",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"
@@ -1747,7 +1752,8 @@
         "contact",
         "protect",
         "mirror",
-        "punch"
+        "punch",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"
@@ -2580,7 +2586,8 @@
       "flags": [
         "contact",
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_hit_move"
@@ -2616,7 +2623,8 @@
       "flags": [
         "contact",
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"
@@ -3681,7 +3689,8 @@
       "category": "special",
       "flags": [
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "fire_spin"
@@ -4263,7 +4272,8 @@
       "flags": [
         "contact",
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"
@@ -4299,7 +4309,8 @@
       "flags": [
         "contact",
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"
@@ -5726,7 +5737,8 @@
       "category": "physical",
       "flags": [
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"
@@ -6579,7 +6591,8 @@
       "category": "special",
       "flags": [
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "magma_storm"
@@ -7895,7 +7908,8 @@
       "category": "physical",
       "flags": [
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"
@@ -9068,7 +9082,8 @@
       "category": "physical",
       "flags": [
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"
@@ -10663,7 +10678,8 @@
       "category": "physical",
       "flags": [
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"
@@ -11540,7 +11556,8 @@
       "flags": [
         "contact",
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"
@@ -12168,7 +12185,8 @@
       "flags": [
         "contact",
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "triple_kick"
@@ -12224,7 +12242,8 @@
       "category": "physical",
       "flags": [
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "twineedle"
@@ -12550,7 +12569,8 @@
       "category": "special",
       "flags": [
         "protect",
-        "mirror"
+        "mirror",
+        "multi_hit"
       ],
       "effect": {
         "name": "2_5_hit_move"

Plugins/PkmnLib.Plugin.Gen7/Gen7Plugin.cs

@@ -1,3 +1,5 @@
+using PkmnLib.Dynamic.Plugins;
+using PkmnLib.Plugin.Gen7.AI;
 using PkmnLib.Plugin.Gen7.Libraries.Battling;
 using PkmnLib.Static.Libraries;
 using PkmnLib.Static.Species;
@@ -47,6 +49,8 @@ public class Gen7Plugin : Plugin<Gen7PluginConfiguration>, IResourceProvider
         registry.RegisterDamageCalculator(new Gen7DamageCalculator(Configuration));
         registry.RegisterMiscLibrary(new Gen7MiscLibrary());
         registry.RegisterCaptureLibrary(new Gen7CaptureLibrary(Configuration));
+
+        ExplicitAIFunctions.RegisterAIFunctions(registry.ExplicitAIHandlers);
     }
 
     /// <inheritdoc />

Plugins/PkmnLib.Plugin.Gen7/Libraries/Battling/Gen7BattleStatCalculator.cs

@@ -40,7 +40,7 @@ public class Gen7BattleStatCalculator : IBattleStatCalculator
     public uint CalculateBoostedStat(IPokemon pokemon, Statistic stat)
     {
         var flatStat = CalculateFlatStat(pokemon, stat);
-        var boostModifier = GetStatBoostModifier(pokemon, stat);
+        var boostModifier = GetStatBoostModifier(pokemon.StatBoost.GetStatistic(stat));
         var boostedStat = flatStat * boostModifier;
         if (boostedStat > uint.MaxValue)
             boostedStat = uint.MaxValue;
@@ -71,13 +71,7 @@ public class Gen7BattleStatCalculator : IBattleStatCalculator
         if (ignoreEvasion)
             targetEvasion = 0;
         var userAccuracy = executingMove.User.StatBoost.Accuracy;
-        var difference = targetEvasion - userAccuracy;
-        var statModifier = difference switch
-        {
-            > 0 => 3.0f / (3.0f + Math.Min(difference, 6)),
-            < 0 => 3.0f + -Math.Max(difference, -6) / 3.0f,
-            _ => 1.0f,
-        };
+        var statModifier = GetAccuracyEvasionStatModifier(targetEvasion, userAccuracy);
         modifiedAccuracy = (int)(modifiedAccuracy * statModifier);
         modifiedAccuracy = modifiedAccuracy switch
         {
@@ -116,10 +110,9 @@ public class Gen7BattleStatCalculator : IBattleStatCalculator
         return (uint)modified;
     }
 
-    private static float GetStatBoostModifier(IPokemon pokemon, Statistic statistic)
+    public static float GetStatBoostModifier(sbyte amount)
     {
-        var boost = pokemon.StatBoost.GetStatistic(statistic);
-        return boost switch
+        return amount switch
         {
             -6 => 2.0f / 8.0f,
             -5 => 2.0f / 7.0f,
@@ -134,7 +127,18 @@ public class Gen7BattleStatCalculator : IBattleStatCalculator
             4 => 6.0f / 2.0f,
             5 => 7.0f / 2.0f,
             6 => 8.0f / 2.0f,
-            _ => throw new ArgumentException($"Stat boost was out of expected range of -6 to 6: {boost}"),
+            _ => throw new ArgumentException($"Stat boost was out of expected range of -6 to 6: {amount}"),
+        };
+    }
+
+    public static float GetAccuracyEvasionStatModifier(sbyte evasion, sbyte accuracy)
+    {
+        var difference = evasion - accuracy;
+        return difference switch
+        {
+            > 0 => 3.0f / (3.0f + Math.Min(difference, 6)),
+            < 0 => 3.0f + -Math.Max(difference, -6) / 3.0f,
+            _ => 1.0f,
         };
     }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Abilities/DrySkin.cs

@@ -8,7 +8,7 @@ namespace PkmnLib.Plugin.Gen7.Scripts.Abilities;
 /// <see href="https://bulbapedia.bulbagarden.net/wiki/Dry_Skin_(Ability)">Bulbapedia - Dry Skin</see>
 /// </summary>
 [Script(ScriptCategory.Ability, "dry_skin")]
-public class DrySkin : Script, IScriptChangeDamageModifier, IScriptOnEndTurn
+public class DrySkin : Script, IScriptChangeDamageModifier, IScriptOnEndTurn, IAIInfoScriptExpectedEndOfTurnDamage
 {
     private IPokemon? _owningPokemon;
 
@@ -55,4 +55,13 @@ public class DrySkin : Script, IScriptChangeDamageModifier, IScriptOnEndTurn
             _owningPokemon.Damage(_owningPokemon.MaxHealth / 8, DamageSource.Weather);
         }
     }
+
+    /// <inheritdoc />
+    public void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        if (pokemon.BattleData?.Battle.WeatherName == ScriptUtils.ResolveName<Weather.HarshSunlight>())
+        {
+            damage += (int)(pokemon.MaxHealth / 8f);
+        }
+    }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Abilities/SolarPower.cs

@@ -6,7 +6,8 @@ namespace PkmnLib.Plugin.Gen7.Scripts.Abilities;
 /// <see href="https://bulbapedia.bulbagarden.net/wiki/Solar_Power_(Ability)">Bulbapedia - Solar Power</see>
 /// </summary>
 [Script(ScriptCategory.Ability, "solar_power")]
-public class SolarPower : Script, IScriptChangeOffensiveStatValue, IScriptOnEndTurn
+public class SolarPower : Script, IScriptChangeOffensiveStatValue, IScriptOnEndTurn,
+    IAIInfoScriptExpectedEndOfTurnDamage
 {
     /// <inheritdoc />
     public void ChangeOffensiveStatValue(IExecutingMove move, IPokemon target, byte hit, uint defensiveStat,
@@ -29,6 +30,26 @@ public class SolarPower : Script, IScriptChangeOffensiveStatValue, IScriptOnEndT
         if (!pokemon.IsUsable)
             return;
 
+        var weatherName = pokemon.BattleData?.Battle.WeatherName;
+        if (weatherName != ScriptUtils.ResolveName<Weather.HarshSunlight>() &&
+            weatherName != ScriptUtils.ResolveName<Weather.DesolateLands>())
+        {
+            return;
+        }
+
         pokemon.Damage(pokemon.MaxHealth / 8, DamageSource.Weather);
     }
+
+    /// <inheritdoc />
+    public void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        var weatherName = pokemon.BattleData?.Battle.WeatherName;
+        if (weatherName != ScriptUtils.ResolveName<Weather.HarshSunlight>() &&
+            weatherName != ScriptUtils.ResolveName<Weather.DesolateLands>())
+        {
+            return;
+        }
+
+        damage += (int)(pokemon.MaxHealth / 8f);
+    }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Moves/ChangeUserStats.cs

@@ -1,3 +1,6 @@
+using PkmnLib.Dynamic.AI.Explicit;
+using PkmnLib.Plugin.Gen7.AI;
+
 namespace PkmnLib.Plugin.Gen7.Scripts.Moves;
 
 public abstract class ChangeUserStats : Script, IScriptOnInitialize, IScriptOnSecondaryEffect
@@ -31,6 +34,19 @@ public abstract class ChangeUserStats : Script, IScriptOnInitialize, IScriptOnSe
     {
         move.User.ChangeStatBoost(_stat, _amount, true, false);
     }
+
+    protected static void GetMoveEffectScore(MoveOption option, Statistic stat, ref int score)
+    {
+        if (option.Move.Move.SecondaryEffect == null ||
+            !option.Move.Move.SecondaryEffect.Parameters.TryGetValue("amount", out var amountObj) ||
+            amountObj is not int amount)
+        {
+            return;
+        }
+        var statisticSet = new StatBoostStatisticSet();
+        statisticSet.SetStatistic(stat, (sbyte)amount);
+        score = AIHelperFunctions.GetScoreForTargetStatRaise(score, option.Move, option.Move.User, statisticSet);
+    }
 }
 
 [Script(ScriptCategory.Move, "change_user_attack")]
@@ -39,6 +55,10 @@ public class ChangeUserAttack : ChangeUserStats
     public ChangeUserAttack() : base(Statistic.Attack)
     {
     }
+
+    [AIMoveScoreFunction]
+    public static void AIMoveEffectScore(MoveOption option, ref int score) =>
+        GetMoveEffectScore(option, Statistic.Attack, ref score);
 }
 
 [Script(ScriptCategory.Move, "change_user_defense")]
@@ -47,6 +67,10 @@ public class ChangeUserDefense : ChangeUserStats
     public ChangeUserDefense() : base(Statistic.Defense)
     {
     }
+
+    [AIMoveScoreFunction]
+    public static void AIMoveEffectScore(MoveOption option, ref int score) =>
+        GetMoveEffectScore(option, Statistic.Defense, ref score);
 }
 
 [Script(ScriptCategory.Move, "change_user_special_attack")]
@@ -55,6 +79,10 @@ public class ChangeUserSpecialAttack : ChangeUserStats
     public ChangeUserSpecialAttack() : base(Statistic.SpecialAttack)
     {
     }
+
+    [AIMoveScoreFunction]
+    public static void AIMoveEffectScore(MoveOption option, ref int score) =>
+        GetMoveEffectScore(option, Statistic.SpecialAttack, ref score);
 }
 
 [Script(ScriptCategory.Move, "change_user_special_defense")]
@@ -63,6 +91,10 @@ public class ChangeUserSpecialDefense : ChangeUserStats
     public ChangeUserSpecialDefense() : base(Statistic.SpecialDefense)
     {
     }
+
+    [AIMoveScoreFunction]
+    public static void AIMoveEffectScore(MoveOption option, ref int score) =>
+        GetMoveEffectScore(option, Statistic.SpecialDefense, ref score);
 }
 
 [Script(ScriptCategory.Move, "change_user_speed")]
@@ -71,6 +103,10 @@ public class ChangeUserSpeed : ChangeUserStats
     public ChangeUserSpeed() : base(Statistic.Speed)
     {
     }
+
+    [AIMoveScoreFunction]
+    public static void AIMoveEffectScore(MoveOption option, ref int score) =>
+        GetMoveEffectScore(option, Statistic.Speed, ref score);
 }
 
 [Script(ScriptCategory.Move, "change_user_accuracy")]
@@ -79,6 +115,10 @@ public class ChangeUserAccuracy : ChangeUserStats
     public ChangeUserAccuracy() : base(Statistic.Accuracy)
     {
     }
+
+    [AIMoveScoreFunction]
+    public static void AIMoveEffectScore(MoveOption option, ref int score) =>
+        GetMoveEffectScore(option, Statistic.Accuracy, ref score);
 }
 
 [Script(ScriptCategory.Move, "change_user_evasion")]
@@ -87,4 +127,8 @@ public class ChangeUserEvasion : ChangeUserStats
     public ChangeUserEvasion() : base(Statistic.Evasion)
     {
     }
+
+    [AIMoveScoreFunction]
+    public static void AIMoveEffectScore(MoveOption option, ref int score) =>
+        GetMoveEffectScore(option, Statistic.Evasion, ref score);
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Moves/MirrorMove.cs

@@ -13,11 +13,13 @@ public class MirrorMove : Script, IScriptChangeMove
             return;
 
         var battle = battleData.Battle;
-        var currentTurn = battle.ChoiceQueue!.LastRanChoice;
+        if (battle.ChoiceQueue == null)
+            return;
+        var currentTurn = battle.ChoiceQueue.LastRanChoice;
         var lastMove = battle.PreviousTurnChoices.SelectMany(x => x).OfType<IMoveChoice>()
-            .TakeWhile(x => x != currentTurn).LastOrDefault(x => x.TargetPosition == choice.TargetPosition &&
-                                                                 x.TargetSide == choice.TargetSide &&
-                                                                 x.User.BattleData?.IsOnBattlefield == true);
+            .TakeWhile(x => !Equals(x, currentTurn)).LastOrDefault(x => x.TargetPosition == choice.TargetPosition &&
+                                                                        x.TargetSide == choice.TargetSide &&
+                                                                        x.User.BattleData?.IsOnBattlefield == true);
         if (lastMove == null || !lastMove.ChosenMove.MoveData.CanCopyMove())
         {
             choice.Fail();

Plugins/PkmnLib.Plugin.Gen7/Scripts/Pokemon/BindEffect.cs

@@ -1,7 +1,8 @@
 namespace PkmnLib.Plugin.Gen7.Scripts.Pokemon;
 
 [Script(ScriptCategory.Pokemon, "bind")]
-public class BindEffect : Script, IScriptOnEndTurn, IScriptPreventSelfSwitch, IScriptPreventSelfRunAway
+public class BindEffect : Script, IScriptOnEndTurn, IScriptPreventSelfSwitch, IScriptPreventSelfRunAway,
+    IAIInfoScriptExpectedEndOfTurnDamage
 {
     private readonly IPokemon? _owner;
     private int _turns;
@@ -33,4 +34,10 @@ public class BindEffect : Script, IScriptOnEndTurn, IScriptPreventSelfSwitch, IS
 
     /// <inheritdoc />
     public void PreventSelfRunAway(IFleeChoice choice, ref bool prevent) => prevent = _turns > 0;
+
+    /// <inheritdoc />
+    public void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        damage += (int)(_owner?.MaxHealth * _percentOfMaxHealth ?? 0);
+    }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Pokemon/FireSpinEffect.cs

@@ -1,7 +1,8 @@
 namespace PkmnLib.Plugin.Gen7.Scripts.Pokemon;
 
 [Script(ScriptCategory.Pokemon, "fire_spin")]
-public class FireSpinEffect : Script, IScriptOnEndTurn, IScriptPreventSelfRunAway, IScriptPreventSelfSwitch
+public class FireSpinEffect : Script, IScriptOnEndTurn, IScriptPreventSelfRunAway, IScriptPreventSelfSwitch,
+    IAIInfoScriptExpectedEndOfTurnDamage
 {
     private readonly IPokemon _owner;
 
@@ -21,4 +22,10 @@ public class FireSpinEffect : Script, IScriptOnEndTurn, IScriptPreventSelfRunAwa
 
     /// <inheritdoc />
     public void PreventSelfSwitch(ISwitchChoice choice, ref bool prevent) => prevent = true;
+
+    /// <inheritdoc />
+    public void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        damage += (int)(pokemon.MaxHealth / 8f);
+    }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Pokemon/GhostCurseEffect.cs

@@ -1,7 +1,7 @@
 namespace PkmnLib.Plugin.Gen7.Scripts.Pokemon;
 
 [Script(ScriptCategory.Pokemon, "ghostcurse")]
-public class GhostCurseEffect : Script, IScriptOnEndTurn
+public class GhostCurseEffect : Script, IScriptOnEndTurn, IAIInfoScriptExpectedEndOfTurnDamage
 {
     private IPokemon _pokemon;
 
@@ -15,4 +15,10 @@ public class GhostCurseEffect : Script, IScriptOnEndTurn
     {
         _pokemon.Damage(_pokemon.CurrentHealth / 4, DamageSource.Misc);
     }
+
+    /// <inheritdoc />
+    public void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        damage += (int)(_pokemon.CurrentHealth / 4f);
+    }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Pokemon/InfestationEffect.cs

@@ -1,7 +1,8 @@
 namespace PkmnLib.Plugin.Gen7.Scripts.Pokemon;
 
 [Script(ScriptCategory.Pokemon, "infestation")]
-public class InfestationEffect : Script, IScriptOnEndTurn, IScriptPreventSelfSwitch, IScriptPreventSelfRunAway
+public class InfestationEffect : Script, IScriptOnEndTurn, IScriptPreventSelfSwitch, IScriptPreventSelfRunAway,
+    IAIInfoScriptExpectedEndOfTurnDamage
 {
     private readonly IPokemon _owner;
     private int _turns;
@@ -30,4 +31,10 @@ public class InfestationEffect : Script, IScriptOnEndTurn, IScriptPreventSelfSwi
             RemoveSelf();
         }
     }
+
+    /// <inheritdoc />
+    public void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        damage += (int)(_owner.MaxHealth / 8f);
+    }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Pokemon/LeechSeedEffect.cs

@@ -1,7 +1,7 @@
 namespace PkmnLib.Plugin.Gen7.Scripts.Pokemon;
 
 [Script(ScriptCategory.Pokemon, "leech_seed")]
-public class LeechSeedEffect : Script, IScriptOnEndTurn
+public class LeechSeedEffect : Script, IScriptOnEndTurn, IAIInfoScriptExpectedEndOfTurnDamage
 {
     private readonly IPokemon _owner;
     private readonly IPokemon _placer;
@@ -15,7 +15,7 @@ public class LeechSeedEffect : Script, IScriptOnEndTurn
     /// <inheritdoc />
     public void OnEndTurn(IScriptSource owner, IBattle battle)
     {
-        var damage = _owner.BoostedStats.Hp / 8;
+        var damage = _owner.MaxHealth / 8;
         if (_owner.CurrentHealth <= damage)
             damage = _owner.CurrentHealth;
 
@@ -25,4 +25,10 @@ public class LeechSeedEffect : Script, IScriptOnEndTurn
         else
             _placer.Heal(damage);
     }
+
+    /// <inheritdoc />
+    public void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        damage += (int)(_owner.MaxHealth / 8f);
+    }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Pokemon/MagmaStormEffect.cs

@@ -1,7 +1,8 @@
 namespace PkmnLib.Plugin.Gen7.Scripts.Pokemon;
 
 [Script(ScriptCategory.Pokemon, "magma_storm")]
-public class MagmaStormEffect : Script, IScriptOnEndTurn, IScriptPreventSelfRunAway, IScriptPreventSelfSwitch
+public class MagmaStormEffect : Script, IScriptOnEndTurn, IScriptPreventSelfRunAway, IScriptPreventSelfSwitch,
+    IAIInfoScriptExpectedEndOfTurnDamage
 {
     private readonly IPokemon _owner;
 
@@ -21,4 +22,10 @@ public class MagmaStormEffect : Script, IScriptOnEndTurn, IScriptPreventSelfRunA
 
     /// <inheritdoc />
     public void PreventSelfSwitch(ISwitchChoice choice, ref bool prevent) => prevent = true;
+
+    /// <inheritdoc />
+    public void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        damage += (int)(pokemon.MaxHealth / 16f);
+    }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Pokemon/NightmareEffect.cs

@@ -3,7 +3,7 @@ using PkmnLib.Plugin.Gen7.Scripts.Status;
 namespace PkmnLib.Plugin.Gen7.Scripts.Pokemon;
 
 [Script(ScriptCategory.Pokemon, "nightmare")]
-public class NightmareEffect : Script, IScriptOnEndTurn
+public class NightmareEffect : Script, IScriptOnEndTurn, IAIInfoScriptExpectedEndOfTurnDamage
 {
     private readonly IPokemon _owner;
 
@@ -23,4 +23,10 @@ public class NightmareEffect : Script, IScriptOnEndTurn
         var maxHp = _owner.MaxHealth;
         _owner.Damage(maxHp / 4, DamageSource.Misc);
     }
+
+    /// <inheritdoc />
+    public void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        damage += (int)(_owner.MaxHealth / 4f);
+    }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Pokemon/SubstituteEffect.cs

@@ -3,7 +3,7 @@ namespace PkmnLib.Plugin.Gen7.Scripts.Pokemon;
 [Script(ScriptCategory.Pokemon, "substitute")]
 public class SubstituteEffect(uint health) : Script, IScriptBlockIncomingHit
 {
-    private uint _health = health;
+    public uint Health { get; private set; } = health;
 
     /// <inheritdoc />
     public void BlockIncomingHit(IExecutingMove executingMove, IPokemon target, byte hitIndex, ref bool block)
@@ -19,12 +19,12 @@ public class SubstituteEffect(uint health) : Script, IScriptBlockIncomingHit
 
         block = true;
         var damage = executingMove.GetHitData(target, hitIndex).Damage;
-        if (damage >= _health)
+        if (damage >= Health)
         {
             executingMove.Battle.EventHook.Invoke(new DialogEvent("substitute_broken"));
             RemoveSelf();
             return;
         }
-        _health -= damage;
+        Health -= damage;
     }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Pokemon/WhirlpoolEffect.cs

@@ -1,7 +1,8 @@
 namespace PkmnLib.Plugin.Gen7.Scripts.Pokemon;
 
 [Script(ScriptCategory.Pokemon, "whirlpool")]
-public class WhirlpoolEffect : Script, IScriptOnEndTurn, IScriptPreventOpponentRunAway, IScriptPreventOpponentSwitch
+public class WhirlpoolEffect : Script, IScriptOnEndTurn, IScriptPreventOpponentRunAway, IScriptPreventOpponentSwitch,
+    IAIInfoScriptExpectedEndOfTurnDamage
 {
     public record PokemonTurn
     {
@@ -80,4 +81,14 @@ public class WhirlpoolEffect : Script, IScriptOnEndTurn, IScriptPreventOpponentR
             _targetedPokemon.Remove(turn);
         }
     }
+
+    /// <inheritdoc />
+    public void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        var turn = _targetedPokemon.FirstOrDefault(x => x.Pokemon == pokemon);
+        if (turn != null)
+        {
+            damage += (int)(pokemon.MaxHealth * turn.DamagePercent);
+        }
+    }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Status/BadlyPoisoned.cs

@@ -1,7 +1,7 @@
 namespace PkmnLib.Plugin.Gen7.Scripts.Status;
 
 [Script(ScriptCategory.Status, "badly_poisoned")]
-public class BadlyPoisoned : Poisoned, IScriptOnEndTurn
+public class BadlyPoisoned : Poisoned
 {
     private int _turns = 1;
 

Plugins/PkmnLib.Plugin.Gen7/Scripts/Status/Burned.cs

@@ -3,7 +3,7 @@ using PkmnLib.Static.Moves;
 namespace PkmnLib.Plugin.Gen7.Scripts.Status;
 
 [Script(ScriptCategory.Status, "burned")]
-public class Burned : Script, IScriptChangeMoveDamage, IScriptOnEndTurn
+public class Burned : Script, IScriptChangeMoveDamage, IScriptOnEndTurn, IAIInfoScriptExpectedEndOfTurnDamage
 {
     private IPokemon? _target;
 
@@ -41,4 +41,11 @@ public class Burned : Script, IScriptChangeMoveDamage, IScriptOnEndTurn
         });
         _target.Damage(damage, DamageSource.Status, eventBatch);
     }
+
+    /// <inheritdoc />
+    public void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        if (_target != null)
+            damage += (int)(_target.MaxHealth / 16f);
+    }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Status/Poisoned.cs

@@ -1,7 +1,7 @@
 namespace PkmnLib.Plugin.Gen7.Scripts.Status;
 
 [Script(ScriptCategory.Status, "poisoned")]
-public class Poisoned : Script, IScriptOnEndTurn
+public class Poisoned : Script, IScriptOnEndTurn, IAIInfoScriptExpectedEndOfTurnDamage
 {
     private IPokemon? _pokemon;
 
@@ -46,4 +46,11 @@ public class Poisoned : Script, IScriptOnEndTurn
         else
             _pokemon.Damage(damage, DamageSource.Status, eventBatchId);
     }
+
+    /// <inheritdoc />
+    public virtual void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        if (_pokemon != null)
+            damage += (int)(_pokemon.MaxHealth * GetPoisonMultiplier());
+    }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Status/Sleep.cs

@@ -1,7 +1,7 @@
 namespace PkmnLib.Plugin.Gen7.Scripts.Status;
 
 [Script(ScriptCategory.Status, "sleep")]
-public class Sleep : Script, IScriptPreventMove
+public class Sleep : Script, IScriptPreventMove, IAIInfoScriptNumberTurnsLeft
 {
     private IPokemon? _pokemon;
     public int Turns { get; set; }
@@ -54,4 +54,7 @@ public class Sleep : Script, IScriptPreventMove
             { "pokemon", _pokemon },
         }));
     }
+
+    /// <inheritdoc />
+    public int TurnsLeft() => Turns;
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Terrain/PsychicTerrain.cs

@@ -27,7 +27,7 @@ public class PsychicTerrain : Script, IScriptIsInvulnerableToMove, IScriptChange
         if (!IsAffectedByTerrain(target))
             return;
 
-        // Psychic Terrain prevents priority moves from affecting affected Pokémon.
+        // Psychic Terrain prevents priority moves from affected Pokémon.
         if (move.MoveChoice.Priority > 0)
         {
             invulnerable = true;

Plugins/PkmnLib.Plugin.Gen7/Scripts/Weather/Hail.cs

@@ -1,7 +1,7 @@
 namespace PkmnLib.Plugin.Gen7.Scripts.Weather;
 
 [Script(ScriptCategory.Weather, "hail")]
-public class Hail : Script, ILimitedTurnsScript, IScriptOnEndTurn
+public class Hail : Script, ILimitedTurnsScript, IScriptOnEndTurn, IAIInfoScriptExpectedEndOfTurnDamage
 {
     private int? _duration;
 
@@ -46,4 +46,15 @@ public class Hail : Script, ILimitedTurnsScript, IScriptOnEndTurn
             battle.SetWeather(null, 0);
         }
     }
+
+    /// <inheritdoc />
+    public void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        if (pokemon.Types.Any(x => x.Name == "ice"))
+            return; // Ice types are immune to Hail damage.
+        if (_duration.HasValue)
+        {
+            damage += (int)(pokemon.MaxHealth / 16f);
+        }
+    }
 }

Plugins/PkmnLib.Plugin.Gen7/Scripts/Weather/Sandstorm.cs

@@ -1,7 +1,8 @@
 namespace PkmnLib.Plugin.Gen7.Scripts.Weather;
 
 [Script(ScriptCategory.Weather, "sandstorm")]
-public class Sandstorm : Script, IScriptChangeBasePower, IScriptChangeDefensiveStatValue, IScriptOnEndTurn
+public class Sandstorm : Script, IScriptChangeBasePower, IScriptChangeDefensiveStatValue, IScriptOnEndTurn,
+    IAIInfoScriptExpectedEndOfTurnDamage
 {
     /// <inheritdoc />
     public void OnEndTurn(IScriptSource owner, IBattle battle)
@@ -39,4 +40,12 @@ public class Sandstorm : Script, IScriptChangeBasePower, IScriptChangeDefensiveS
         if (move.UseMove.Name == "solar_beam")
             basePower /= 2;
     }
+
+    /// <inheritdoc />
+    public void ExpectedEndOfTurnDamage(IPokemon pokemon, ref int damage)
+    {
+        if (pokemon.Types.Any(x => x.Name == "rock" || x.Name == "ground" || x.Name == "steel"))
+            return; // Rock, Ground, and Steel types are immune to Sandstorm damage.
+        damage += (int)(pokemon.MaxHealth / 16f);
+    }
 }