More abilities, refactor custom triggers to be typed.

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

@@ -0,0 +1,22 @@
+using PkmnLib.Plugin.Gen7.Scripts.Status;
+
+namespace PkmnLib.Plugin.Gen7.Scripts.Abilities;
+
+/// <summary>
+/// Merciless is an ability that always results in critical hits against poisoned targets.
+///
+/// <see href="https://bulbapedia.bulbagarden.net/wiki/Merciless_(Ability)">Bulbapedia - Merciless</see>
+/// </summary>
+[Script(ScriptCategory.Ability, "merciless")]
+public class Merciless : Script
+{
+    /// <inheritdoc />
+    public override void ChangeCriticalStage(IExecutingMove move, IPokemon target, byte hit, ref byte stage)
+    {
+        if (target.StatusScript.Script?.Name == ScriptUtils.ResolveName<Poisoned>() ||
+            target.StatusScript.Script?.Name == ScriptUtils.ResolveName<BadlyPoisoned>())
+        {
+            stage = 100;
+        }
+    }
+}