Implements more move effects

Plugins/PkmnLib.Plugin.Gen7/Scripts/Battle/Gravity.cs

@@ -0,0 +1,35 @@
+using System.Linq;
+
+namespace PkmnLib.Plugin.Gen7.Scripts.Battle;
+
+[Script(ScriptCategory.Battle, "gravity")]
+public class Gravity : Script
+{
+    /// <inheritdoc />
+    public override void ChangeEffectiveness(IExecutingMove move, IPokemon target, byte hit, ref float effectiveness)
+    {
+        var battleData = target.BattleData;
+        if (battleData == null)
+            return;
+
+        if (move.UseMove.MoveType.Name == "ground")
+        {
+            var targetTypes = target.Types;
+            var typeLibrary = battleData.Battle.Library.StaticLibrary.Types;
+            effectiveness =
+                // Get the effectiveness of the move against each target type
+                targetTypes.Select(x => typeLibrary.GetSingleEffectiveness(move.UseMove.MoveType, x))
+                    // Ignore all types that are immune to ground moves
+                    .Where(x => x > 0)
+                    // Multiply all effectiveness values together
+                    .Aggregate(1.0f, (current, x) => current * x);
+        }
+    }
+
+    /// <inheritdoc />
+    public override void FailIncomingMove(IExecutingMove move, IPokemon target, ref bool fail)
+    {
+        if (move.UseMove.HasFlag("gravity"))
+            fail = true;
+    }
+}