diff --git a/src/data/ability.ts b/src/data/ability.ts
index f4701d3a4e1..950538af9f6 100644
--- a/src/data/ability.ts
+++ b/src/data/ability.ts
@@ -6,7 +6,7 @@ import { BattleStat, getBattleStatName } from "./battle-stat";
 import { MovePhase, PokemonHealPhase, ShowAbilityPhase, StatChangePhase } from "../phases";
 import { getPokemonNameWithAffix } from "../messages";
 import { Weather, WeatherType } from "./weather";
-import { BattlerTag, GroundedTag, GulpMissileTag } from "./battler-tags";
+import { BattlerTag, GroundedTag, GulpMissileTag, SemiInvulnerableTag } from "./battler-tags";
 import { StatusEffect, getNonVolatileStatusEffects, getStatusEffectDescriptor, getStatusEffectHealText } from "./status-effect";
 import { Gender } from "./gender";
 import Move, { AttackMove, MoveCategory, MoveFlags, MoveTarget, FlinchAttr, OneHitKOAttr, HitHealAttr, allMoves, StatusMove, SelfStatusMove, VariablePowerAttr, applyMoveAttrs, IncrementMovePriorityAttr, VariableMoveTypeAttr, RandomMovesetMoveAttr, RandomMoveAttr, NaturePowerAttr, CopyMoveAttr, MoveAttr, MultiHitAttr, ChargeAttr, SacrificialAttr, SacrificialAttrOnHit } from "./move";
@@ -517,7 +517,7 @@ export class PostDefendGulpMissileAbAttr extends PostDefendAbAttr {
    */
   applyPostDefend(pokemon: Pokemon, passive: boolean, attacker: Pokemon, move: Move, hitResult: HitResult, args: any[]): boolean | Promise<boolean> {
     const battlerTag = pokemon.getTag(GulpMissileTag);
-    if (!battlerTag || move.category === MoveCategory.STATUS) {
+    if (!battlerTag || move.category === MoveCategory.STATUS || pokemon.getTag(SemiInvulnerableTag)) {
       return false;
     }
 
@@ -5138,9 +5138,7 @@ export function initAbilities() {
       .attr(NoFusionAbilityAbAttr)
       .attr(UncopiableAbilityAbAttr)
       .attr(UnswappableAbilityAbAttr)
-      .attr(PostDefendGulpMissileAbAttr)
-      // Does not transform when Surf/Dive misses/is protected
-      .partial(),
+      .attr(PostDefendGulpMissileAbAttr),
     new Ability(Abilities.STALWART, 8)
       .attr(BlockRedirectAbAttr),
     new Ability(Abilities.STEAM_ENGINE, 8)
diff --git a/src/data/move.ts b/src/data/move.ts
index c43150992bc..2d0ea11c3a0 100644
--- a/src/data/move.ts
+++ b/src/data/move.ts
@@ -4356,7 +4356,7 @@ export class AddBattlerTagAttr extends MoveEffectAttr {
  */
 export class GulpMissileTagAttr extends MoveEffectAttr {
   constructor() {
-    super(true, MoveEffectTrigger.POST_APPLY);
+    super(true);
   }
 
   /**
@@ -6954,7 +6954,7 @@ export function initMoves() {
       .makesContact(false)
       .partial(),
     new AttackMove(Moves.DIVE, Type.WATER, MoveCategory.PHYSICAL, 80, 100, 10, -1, 0, 3)
-      .attr(ChargeAttr, ChargeAnim.DIVE_CHARGING, i18next.t("moveTriggers:hidUnderwater", {pokemonName: "{USER}"}), BattlerTagType.UNDERWATER)
+      .attr(ChargeAttr, ChargeAnim.DIVE_CHARGING, i18next.t("moveTriggers:hidUnderwater", {pokemonName: "{USER}"}), BattlerTagType.UNDERWATER, true)
       .attr(GulpMissileTagAttr)
       .ignoresVirtual(),
     new AttackMove(Moves.ARM_THRUST, Type.FIGHTING, MoveCategory.PHYSICAL, 15, 100, 20, -1, 0, 3)
diff --git a/src/form-change-phase.ts b/src/form-change-phase.ts
index 55bf655081b..5acbc4fb77c 100644
--- a/src/form-change-phase.ts
+++ b/src/form-change-phase.ts
@@ -11,6 +11,7 @@ import { BattleSpec } from "#enums/battle-spec";
 import { BattlePhase, MovePhase, PokemonHealPhase } from "./phases";
 import { getTypeRgb } from "./data/type";
 import { getPokemonNameWithAffix } from "./messages";
+import { SemiInvulnerableTag } from "./data/battler-tags";
 
 export class FormChangePhase extends EvolutionPhase {
   private formChange: SpeciesFormChange;
@@ -194,7 +195,7 @@ export class QuietFormChangePhase extends BattlePhase {
 
     const preName = getPokemonNameWithAffix(this.pokemon);
 
-    if (!this.pokemon.isOnField()) {
+    if (!this.pokemon.isOnField() || this.pokemon.getTag(SemiInvulnerableTag)) {
       this.pokemon.changeForm(this.formChange).then(() => {
         this.scene.ui.showText(getSpeciesFormChangeMessage(this.pokemon, this.formChange, preName), null, () => this.end(), 1500);
       });
diff --git a/src/test/abilities/gulp_missile.test.ts b/src/test/abilities/gulp_missile.test.ts
index b64cbe2ef10..2647f765f6e 100644
--- a/src/test/abilities/gulp_missile.test.ts
+++ b/src/test/abilities/gulp_missile.test.ts
@@ -1,5 +1,6 @@
 import { BattlerTagType } from "#app/enums/battler-tag-type.js";
 import {
+  BerryPhase,
   MoveEndPhase,
   TurnEndPhase,
   TurnStartPhase,
@@ -14,7 +15,6 @@ import { afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "vite
 import { SPLASH_ONLY } from "../utils/testUtils";
 import { BattleStat } from "#app/data/battle-stat.js";
 import { StatusEffect } from "#app/enums/status-effect.js";
-import { GulpMissileTag } from "#app/data/battler-tags.js";
 import Pokemon from "#app/field/pokemon.js";
 
 describe("Abilities - Gulp Missile", () => {
@@ -84,6 +84,17 @@ describe("Abilities - Gulp Missile", () => {
     expect(cramorant.formIndex).toBe(GORGING_FORM);
   });
 
+  it("changes form during Dive's charge turn", async () => {
+    await game.startBattle([Species.CRAMORANT]);
+    const cramorant = game.scene.getPlayerPokemon()!;
+
+    game.doAttack(getMovePosition(game.scene, 0, Moves.DIVE));
+    await game.phaseInterceptor.to(MoveEndPhase);
+
+    expect(cramorant.getTag(BattlerTagType.GULP_MISSILE_ARROKUDA)).toBeDefined();
+    expect(cramorant.formIndex).toBe(GULPING_FORM);
+  });
+
   it("deals ¼ of the attacker's maximum HP when hit by a damaging attack", async () => {
     game.override.enemyMoveset(Array(4).fill(Moves.TACKLE));
     await game.startBattle([Species.CRAMORANT]);
@@ -165,29 +176,16 @@ describe("Abilities - Gulp Missile", () => {
   });
 
   it("does not activate the ability when underwater", async () => {
-    game.override
-      .enemyMoveset(Array(4).fill(Moves.SURF))
-      .enemySpecies(Species.REGIELEKI)
-      .enemyAbility(Abilities.BALL_FETCH)
-      .enemyLevel(5);
+    game.override.enemyMoveset(Array(4).fill(Moves.SURF));
     await game.startBattle([Species.CRAMORANT]);
 
     const cramorant = game.scene.getPlayerPokemon()!;
 
     game.doAttack(getMovePosition(game.scene, 0, Moves.DIVE));
-    await game.toNextTurn();
+    await game.phaseInterceptor.to(BerryPhase, false);
 
-    // Turn 2 underwater, enemy moves first
-    game.doAttack(getMovePosition(game.scene, 0, Moves.DIVE));
-    await game.phaseInterceptor.to(MoveEndPhase);
-
-    expect(cramorant.formIndex).toBe(NORMAL_FORM);
-    expect(cramorant.getTag(GulpMissileTag)).toBeUndefined();
-
-    // Turn 2 Cramorant comes out and changes form
-    await game.phaseInterceptor.to(TurnEndPhase);
-    expect(cramorant.formIndex).not.toBe(NORMAL_FORM);
-    expect(cramorant.getTag(GulpMissileTag)).toBeDefined();
+    expect(cramorant.getTag(BattlerTagType.GULP_MISSILE_ARROKUDA)).toBeDefined();
+    expect(cramorant.formIndex).toBe(GULPING_FORM);
   });
 
   it("prevents effect damage but inflicts secondary effect on attacker with Magic Guard", async () => {