diff --git a/src/data/ability.ts b/src/data/ability.ts
index 429aae7b0dd..edae5aedc35 100644
--- a/src/data/ability.ts
+++ b/src/data/ability.ts
@@ -6248,6 +6248,7 @@ export function initAbilities() {
       .conditionalAttr(p => globalScene.currentBattle.double && [ Abilities.PLUS, Abilities.MINUS ].some(a => p.getAlly().hasAbility(a)), StatMultiplierAbAttr, Stat.SPATK, 1.5),
     new Ability(Abilities.FORECAST, 3)
       .uncopiable()
+      .unreplaceable()
       .attr(NoFusionAbilityAbAttr)
       .attr(PostSummonFormChangeByWeatherAbAttr, Abilities.FORECAST)
       .attr(PostWeatherChangeFormChangeAbAttr, Abilities.FORECAST, [ WeatherType.NONE, WeatherType.SANDSTORM, WeatherType.STRONG_WINDS, WeatherType.FOG ]),
diff --git a/test/abilities/forecast.test.ts b/test/abilities/forecast.test.ts
index 642b490da72..a25af32537d 100644
--- a/test/abilities/forecast.test.ts
+++ b/test/abilities/forecast.test.ts
@@ -210,37 +210,6 @@ describe("Abilities - Forecast", () => {
     expect(game.scene.getEnemyPokemon()?.formIndex).not.toBe(RAINY_FORM);
   });
 
-  it("reverts to Normal Form when Castform loses Forecast, changes form to match the weather when it regains it", async () => {
-    game.override
-      .moveset([Moves.SKILL_SWAP, Moves.WORRY_SEED, Moves.SPLASH])
-      .weather(WeatherType.RAIN)
-      .battleType("double");
-    await game.startBattle([Species.CASTFORM, Species.FEEBAS]);
-
-    const castform = game.scene.getPlayerField()[0];
-
-    expect(castform.formIndex).toBe(RAINY_FORM);
-
-    game.move.select(Moves.SKILL_SWAP, 0, BattlerIndex.PLAYER_2);
-    game.move.select(Moves.SKILL_SWAP, 1, BattlerIndex.PLAYER);
-    await game.setTurnOrder([BattlerIndex.PLAYER, BattlerIndex.PLAYER_2, BattlerIndex.ENEMY, BattlerIndex.ENEMY_2]);
-
-    await game.phaseInterceptor.to("MoveEndPhase");
-    expect(castform.formIndex).toBe(NORMAL_FORM);
-
-    await game.phaseInterceptor.to("MoveEndPhase");
-    expect(castform.formIndex).toBe(RAINY_FORM);
-
-    await game.toNextTurn();
-
-    game.move.select(Moves.SPLASH);
-    game.move.select(Moves.WORRY_SEED, 1, BattlerIndex.PLAYER);
-    await game.setTurnOrder([BattlerIndex.PLAYER_2, BattlerIndex.PLAYER, BattlerIndex.ENEMY, BattlerIndex.ENEMY_2]);
-    await game.phaseInterceptor.to("MoveEndPhase");
-
-    expect(castform.formIndex).toBe(NORMAL_FORM);
-  });
-
   it("reverts to Normal Form when Forecast is suppressed, changes form to match the weather when it regains it", async () => {
     game.override.enemyMoveset([Moves.GASTRO_ACID]).weather(WeatherType.RAIN);
     await game.startBattle([Species.CASTFORM, Species.PIKACHU]);