diff --git a/src/data/ability.ts b/src/data/ability.ts
index 95609fb0831..ea2bad7e092 100644
--- a/src/data/ability.ts
+++ b/src/data/ability.ts
@@ -4687,7 +4687,7 @@ export class TerrainEventTypeChangeAbAttr extends PostSummonAbAttr {
     super(true);
   }
 
-  apply(pokemon: Pokemon, passive: boolean, simulated: boolean, cancelled: Utils.BooleanHolder, args: any[]): boolean {
+  apply(pokemon: Pokemon, _passive: boolean, _simulated: boolean, _cancelled: Utils.BooleanHolder, _args: any[]): boolean {
     if (pokemon.isTerastallized()) {
       return false;
     }
diff --git a/src/field/arena.ts b/src/field/arena.ts
index 52b535ef3bf..09faee49d56 100644
--- a/src/field/arena.ts
+++ b/src/field/arena.ts
@@ -10,7 +10,14 @@ import Move from "#app/data/move";
 import { ArenaTag, ArenaTagSide, ArenaTrapTag, getArenaTag } from "#app/data/arena-tag";
 import { BattlerIndex } from "#app/battle";
 import { Terrain, TerrainType } from "#app/data/terrain";
-import { applyAbAttrs, applyPostTerrainChangeAbAttrs, applyPostWeatherChangeAbAttrs, PostTerrainChangeAbAttr, PostWeatherChangeAbAttr, TerrainEventTypeChangeAbAttr } from "#app/data/ability";
+import {
+  applyAbAttrs,
+  applyPostTerrainChangeAbAttrs,
+  applyPostWeatherChangeAbAttrs,
+  PostTerrainChangeAbAttr,
+  PostWeatherChangeAbAttr,
+  TerrainEventTypeChangeAbAttr
+} from "#app/data/ability";
 import Pokemon from "#app/field/pokemon";
 import Overrides from "#app/overrides";
 import { TagAddedEvent, TagRemovedEvent, TerrainChangedEvent, WeatherChangedEvent } from "#app/events/arena";
diff --git a/src/field/pokemon.ts b/src/field/pokemon.ts
index 2e2254be048..ff096add798 100644
--- a/src/field/pokemon.ts
+++ b/src/field/pokemon.ts
@@ -1245,8 +1245,8 @@ export default abstract class Pokemon extends Phaser.GameObjects.Container {
     }
 
     // the type added to Pokemon from moves like Forest's Curse or Trick Or Treat
-    if (this.summonData?.addedType && !types.includes(this.summonData?.addedType)) {
-      types.push(this.summonData?.addedType);
+    if (this.summonData && this.summonData.addedType && !types.includes(this.summonData.addedType)) {
+      types.push(this.summonData.addedType);
     }
 
     // this.scene potentially can be undefined for a fainted pokemon in doubles
diff --git a/src/test/abilities/mimicry.test.ts b/src/test/abilities/mimicry.test.ts
index a4c6cad496e..d950caa5f48 100644
--- a/src/test/abilities/mimicry.test.ts
+++ b/src/test/abilities/mimicry.test.ts
@@ -38,16 +38,15 @@ describe("Abilities - Mimicry", () => {
     game.override.enemyAbility(Abilities.MISTY_SURGE);
     await game.classicMode.startBattle([ Species.FEEBAS, Species.ABRA ]);
 
-    const playerPokemon1 = game.scene.getPlayerPokemon();
+    const [ playerPokemon1, playerPokemon2 ] = game.scene.getParty();
     game.move.select(Moves.SPLASH);
     await game.toNextTurn();
-    expect(playerPokemon1?.getTypes().includes(Type.FAIRY)).toBe(true);
+    expect(playerPokemon1.getTypes().includes(Type.FAIRY)).toBe(true);
 
     game.doSwitchPokemon(1);
     await game.toNextTurn();
 
-    const playerPokemon2 = game.scene.getPlayerPokemon();
-    expect(playerPokemon2?.getTypes().includes(Type.FAIRY)).toBe(true);
+    expect(playerPokemon2.getTypes().includes(Type.FAIRY)).toBe(true);
   });
 
   it("Pokemon should revert back to its original, root type once terrain ends", async () => {