diff --git a/asm/macros/battle_script.inc b/asm/macros/battle_script.inc
index 260257fc61..34aea69998 100644
--- a/asm/macros/battle_script.inc
+++ b/asm/macros/battle_script.inc
@@ -1635,7 +1635,11 @@
 	.macro trygulpmissile
 	callnative BS_TryGulpMissile
 	.endm
-
+	
+	.macro tryactivategulpmissile
+	callnative BS_TryActivateGulpMissile
+	.endm
+	
 	.macro tryquash failInstr:req
 	callnative BS_TryQuash
 	.4byte \failInstr
diff --git a/data/battle_scripts_1.s b/data/battle_scripts_1.s
index 788b5225f0..79ee6b4017 100644
--- a/data/battle_scripts_1.s
+++ b/data/battle_scripts_1.s
@@ -5458,6 +5458,7 @@ BattleScript_EffectCamouflage::
 
 BattleScript_FaintAttacker::
 	tryillusionoff BS_ATTACKER
+	tryactivategulpmissile
 	playfaintcry BS_ATTACKER
 	pause B_WAIT_TIME_LONG
 	dofaintanimation BS_ATTACKER
@@ -5470,6 +5471,7 @@ BattleScript_FaintAttacker::
 
 BattleScript_FaintTarget::
 	tryillusionoff BS_TARGET
+	tryactivategulpmissile
 	playfaintcry BS_TARGET
 	pause B_WAIT_TIME_LONG
 	dofaintanimation BS_TARGET
diff --git a/include/constants/form_change_types.h b/include/constants/form_change_types.h
index 51325baf25..30bb54d027 100644
--- a/include/constants/form_change_types.h
+++ b/include/constants/form_change_types.h
@@ -120,4 +120,7 @@
 // param1: status
 #define FORM_CHANGE_STATUS                      20
 
+// Form change that activates after move is used. Currently only used for activating Gulp Missile.
+#define FORM_CHANGE_HIT_BY_MOVE                     21
+
 #endif // GUARD_CONSTANTS_FORM_CHANGE_TYPES_H
diff --git a/src/battle_script_commands.c b/src/battle_script_commands.c
index f80bebd8a2..6f57f87e31 100644
--- a/src/battle_script_commands.c
+++ b/src/battle_script_commands.c
@@ -16880,6 +16880,39 @@ void BS_TryGulpMissile(void)
         gBattlescriptCurrInstr = cmd->nextInstr;
 }
 
+void BS_TryActivateGulpMissile(void)
+{
+    NATIVE_ARGS();
+
+    if (!(gMoveResultFlags & MOVE_RESULT_NO_EFFECT)
+        && !gProtectStructs[gBattlerAttacker].confusionSelfDmg
+        && TARGET_TURN_DAMAGED
+        && gBattleMons[gBattlerTarget].species != SPECIES_CRAMORANT
+        && GetBattlerAbility(gBattlerTarget) == ABILITY_GULP_MISSILE)
+    {
+        if (GetBattlerAbility(gBattlerAttacker) != ABILITY_MAGIC_GUARD)
+        {
+            gBattleMoveDamage = GetNonDynamaxMaxHP(gBattlerAttacker) / 4;
+            if (gBattleMoveDamage == 0)
+                gBattleMoveDamage = 1;
+        }
+
+        switch(gBattleMons[gBattlerTarget].species)
+        {
+            case SPECIES_CRAMORANT_GORGING:
+                BattleScriptPushCursor();
+                TryBattleFormChange(gBattlerTarget, FORM_CHANGE_HIT_BY_MOVE);
+                gBattlescriptCurrInstr = BattleScript_GulpMissileGorging;
+                return;
+            case SPECIES_CRAMORANT_GULPING:
+                BattleScriptPushCursor();
+                TryBattleFormChange(gBattlerTarget, FORM_CHANGE_HIT_BY_MOVE);
+                gBattlescriptCurrInstr = BattleScript_GulpMissileGulping;
+                return;
+        }
+    }
+    gBattlescriptCurrInstr = cmd->nextInstr;
+}
 
 void BS_TryQuash(void)
 {
diff --git a/src/battle_util.c b/src/battle_util.c
index efa1a3ecf7..c1f0ac89bf 100644
--- a/src/battle_util.c
+++ b/src/battle_util.c
@@ -5583,34 +5583,30 @@ u32 AbilityBattleEffects(u32 caseID, u32 battler, u32 ability, u32 special, u32
             if (!(gMoveResultFlags & MOVE_RESULT_NO_EFFECT)
              && !gProtectStructs[gBattlerAttacker].confusionSelfDmg
              && TARGET_TURN_DAMAGED
-             && IsBattlerAlive(battler))
+             && IsBattlerAlive(battler)
+             && gBattleMons[gBattlerTarget].species != SPECIES_CRAMORANT)
             {
-                // TODO: Convert this to a proper FORM_CHANGE type.
-                if (gBattleMons[gBattlerTarget].species == SPECIES_CRAMORANT_GORGING)
+                if (GetBattlerAbility(gBattlerAttacker) != ABILITY_MAGIC_GUARD)
                 {
-                    gBattleMons[gBattlerTarget].species = SPECIES_CRAMORANT;
-                    if (GetBattlerAbility(gBattlerAttacker) != ABILITY_MAGIC_GUARD)
-                    {
-                        gBattleMoveDamage = GetNonDynamaxMaxHP(gBattlerAttacker) / 4;
-                        if (gBattleMoveDamage == 0)
-                            gBattleMoveDamage = 1;
-                    }
-                    BattleScriptPushCursor();
-                    gBattlescriptCurrInstr = BattleScript_GulpMissileGorging;
-                    effect++;
+                    gBattleMoveDamage = GetNonDynamaxMaxHP(gBattlerAttacker) / 4;
+                    if (gBattleMoveDamage == 0)
+                        gBattleMoveDamage = 1;
                 }
-                else if (gBattleMons[gBattlerTarget].species == SPECIES_CRAMORANT_GULPING)
+
+                switch(gBattleMons[gBattlerTarget].species)
                 {
-                    gBattleMons[gBattlerTarget].species = SPECIES_CRAMORANT;
-                    if (GetBattlerAbility(gBattlerAttacker) != ABILITY_MAGIC_GUARD)
-                    {
-                        gBattleMoveDamage = GetNonDynamaxMaxHP(gBattlerAttacker) / 4;
-                        if (gBattleMoveDamage == 0)
-                            gBattleMoveDamage = 1;
-                    }
-                    BattleScriptPushCursor();
-                    gBattlescriptCurrInstr = BattleScript_GulpMissileGulping;
-                    effect++;
+                    case SPECIES_CRAMORANT_GORGING:
+                        TryBattleFormChange(battler, FORM_CHANGE_HIT_BY_MOVE);
+                        BattleScriptPushCursor();
+                        gBattlescriptCurrInstr = BattleScript_GulpMissileGorging;
+                        effect++;
+                        break;
+                    case SPECIES_CRAMORANT_GULPING:
+                        TryBattleFormChange(battler, FORM_CHANGE_HIT_BY_MOVE);
+                        BattleScriptPushCursor();
+                        gBattlescriptCurrInstr = BattleScript_GulpMissileGulping;
+                        effect++;
+                        break;
                 }
             }
             break;
@@ -10480,6 +10476,7 @@ u16 GetBattleFormChangeTargetSpecies(u32 battler, u16 method)
                     }
                     break;
                 case FORM_CHANGE_BATTLE_TURN_END:
+                case FORM_CHANGE_HIT_BY_MOVE:
                     if (formChanges[i].param1 == GetBattlerAbility(battler))
                         targetSpecies = formChanges[i].targetSpecies;
                     break;
diff --git a/src/data/pokemon/form_change_tables.h b/src/data/pokemon/form_change_tables.h
index 5edd6f42b5..8eb96e04b0 100644
--- a/src/data/pokemon/form_change_tables.h
+++ b/src/data/pokemon/form_change_tables.h
@@ -1098,6 +1098,7 @@ static const struct FormChange sSandacondaFormChangeTable[] =
 static const struct FormChange sCramorantFormChangeTable[] = {
     {FORM_CHANGE_BATTLE_HP_PERCENT, SPECIES_CRAMORANT_GULPING, ABILITY_GULP_MISSILE, HP_HIGHER_THAN,   50},
     {FORM_CHANGE_BATTLE_HP_PERCENT, SPECIES_CRAMORANT_GORGING, ABILITY_GULP_MISSILE, HP_LOWER_EQ_THAN, 50},
+    {FORM_CHANGE_HIT_BY_MOVE,       SPECIES_CRAMORANT,         ABILITY_GULP_MISSILE},
     {FORM_CHANGE_BATTLE_SWITCH,     SPECIES_CRAMORANT},
     {FORM_CHANGE_FAINT,             SPECIES_CRAMORANT},
     {FORM_CHANGE_END_BATTLE,        SPECIES_CRAMORANT},
diff --git a/test/battle/ability/gulp_missile.c b/test/battle/ability/gulp_missile.c
index 680208506d..2ec9acc61b 100644
--- a/test/battle/ability/gulp_missile.c
+++ b/test/battle/ability/gulp_missile.c
@@ -116,9 +116,7 @@ SINGLE_BATTLE_TEST("(Gulp Missile) Cramorant in Gorging paralyzes the target if
 }
 
 SINGLE_BATTLE_TEST("(Gulp Missile) triggers even if the user is fainted by opposing mon")
-{
-    // See: https://github.com/rh-hideout/pokeemerald-expansion/issues/4143
-    KNOWN_FAILING;
+{  
     GIVEN {
         PLAYER(SPECIES_CRAMORANT) { HP(1); MaxHP(250); Ability(ABILITY_GULP_MISSILE); }
         PLAYER(SPECIES_WOBBUFFET);