More moves, allow for typeless moves

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

@@ -10,7 +10,7 @@ public class PowderEffect : Script
     public override void BlockOutgoingHit(IExecutingMove executingMove, IPokemon target, byte hitIndex, ref bool block)
     {
         var hit = executingMove.GetHitData(target, hitIndex);
-        if (hit.Type.Name == "fire")
+        if (hit.Type?.Name == "fire")
         {
             executingMove.User.BattleData?.Battle.EventHook.Invoke(new DialogEvent("powder_explodes",
                 new Dictionary<string, object>

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

@@ -0,0 +1,19 @@
+using System.Collections.Generic;
+using PkmnLib.Static;
+using PkmnLib.Static.Utils;
+
+namespace PkmnLib.Plugin.Gen7.Scripts.Pokemon;
+
+[Script(ScriptCategory.Pokemon, "roost_effect")]
+public class RoostEffect : Script
+{
+    /// <inheritdoc />
+    public override void ChangeTypesForIncomingMove(IExecutingMove executingMove, IPokemon target, byte hitIndex,
+        IList<TypeIdentifier> types)
+    {
+        types.RemoveAll(x => x.Name == "flying");
+    }
+
+    /// <inheritdoc />
+    public override void OnEndTurn(IBattle battle) => RemoveSelf();
+}