start ability

data/battle_scripts_1.s

@@ -8091,6 +8091,12 @@ BattleScript_SwitchInAbilityMsg::
 	waitmessage B_WAIT_TIME_LONG
 	end3
 
+BattleScript_SwitchInAbilityMsgRet::
+	call BattleScript_AbilityPopUp
+	printfromtable gSwitchInAbilityStringIds
+	waitmessage B_WAIT_TIME_LONG
+	return
+
 BattleScript_ActivateAsOne::
 	call BattleScript_AbilityPopUp
 	printfromtable gSwitchInAbilityStringIds
@@ -8909,3 +8915,14 @@ BattleScript_DarkTypePreventsPrankster::
 	waitmessage B_WAIT_TIME_LONG
 	orhalfword gMoveResultFlags, MOVE_RESULT_NO_EFFECT
 	goto BattleScript_MoveEnd
+
+BattleScript_NeutralizingGasExits::
+	pause B_WAIT_TIME_SHORT
+	printstring STRINGID_NEUTRALIZINGGASOVER
+	waitmessage B_WAIT_TIME_LONG
+	setbyte gBattlerTarget, 0
+BattleScript_NeutralizingGasExitsLoop:
+	switchinabilities BS_TARGET
+	addbyte gBattlerTarget, 1
+	jumpifbytenotequal gBattlerTarget, gBattlersCount, BattleScript_NeutralizingGasExitsLoop
+	return

include/battle.h

@@ -68,6 +68,7 @@ struct ResourceFlags
 #define RESOURCE_FLAG_INTIMIDATED       0x8
 #define RESOURCE_FLAG_TRACED            0x10
 #define RESOURCE_FLAG_EMERGENCY_EXIT    0x20
+#define RESOURCE_FLAG_NEUTRALIZING_GAS  0x40
 
 struct DisableStruct
 {
@@ -181,6 +182,7 @@ struct SpecialStatus
     u8 damagedMons:4; // Mons that have been damaged directly by using a move, includes substitute.
     u8 dancerUsedMove:1;
     u8 dancerOriginalTarget:3;
+    u8 announceNeutralizingGas:1;
     s32 dmg;
     s32 physicalDmg;
     s32 specialDmg;

include/battle_scripts.h

@@ -261,6 +261,7 @@ extern const u8 BattleScript_AttackerAbilityStatRaiseEnd3[];
 extern const u8 BattleScript_PoisonHealActivates[];
 extern const u8 BattleScript_BadDreamsActivates[];
 extern const u8 BattleScript_SwitchInAbilityMsg[];
+extern const u8 BattleScript_SwitchInAbilityMsgRet[];
 extern const u8 BattleScript_ToxicSpikesPoisoned[];
 extern const u8 BattleScript_ToxicSpikesAbsorbed[];
 extern const u8 BattleScript_StickyWebOnSwitchIn[];
@@ -402,5 +403,6 @@ extern const u8 BattleScript_BlockedByPrimalWeatherEnd3[];
 extern const u8 BattleScript_BlockedByPrimalWeatherRet[];
 extern const u8 BattleScript_PrimalReversion[];
 extern const u8 BattleScript_HyperspaceFuryRemoveProtect[];
+extern const u8 BattleScript_NeutralizingGasExits[];
 
 #endif // GUARD_BATTLE_SCRIPTS_H

include/battle_util.h

@@ -8,21 +8,23 @@
 #define MOVE_LIMITATION_TAUNT                   (1 << 4)
 #define MOVE_LIMITATION_IMPRISON                (1 << 5)
 
-#define ABILITYEFFECT_ON_SWITCHIN                0x0
+#define ABILITYEFFECT_ON_SWITCHIN                0
-#define ABILITYEFFECT_ENDTURN                    0x1
+#define ABILITYEFFECT_ENDTURN                    1
-#define ABILITYEFFECT_MOVES_BLOCK                0x2
+#define ABILITYEFFECT_MOVES_BLOCK                2
-#define ABILITYEFFECT_ABSORBING                  0x3
+#define ABILITYEFFECT_ABSORBING                  3
-#define ABILITYEFFECT_MOVE_END_ATTACKER          0x4
+#define ABILITYEFFECT_MOVE_END_ATTACKER          4
-#define ABILITYEFFECT_MOVE_END                   0x5
+#define ABILITYEFFECT_MOVE_END                   5
-#define ABILITYEFFECT_IMMUNITY                   0x6
+#define ABILITYEFFECT_IMMUNITY                   6
-#define ABILITYEFFECT_FORECAST                   0x7
+#define ABILITYEFFECT_FORECAST                   7
-#define ABILITYEFFECT_SYNCHRONIZE                0x8
+#define ABILITYEFFECT_SYNCHRONIZE                8
-#define ABILITYEFFECT_ATK_SYNCHRONIZE            0x9
+#define ABILITYEFFECT_ATK_SYNCHRONIZE            9
-#define ABILITYEFFECT_INTIMIDATE1                0xA
+#define ABILITYEFFECT_INTIMIDATE1                10
-#define ABILITYEFFECT_INTIMIDATE2                0xB
+#define ABILITYEFFECT_INTIMIDATE2                11
-#define ABILITYEFFECT_TRACE1                     0xC
+#define ABILITYEFFECT_TRACE1                     12
-#define ABILITYEFFECT_TRACE2                     0xD
+#define ABILITYEFFECT_TRACE2                     13
-#define ABILITYEFFECT_MOVE_END_OTHER             0xE
+#define ABILITYEFFECT_MOVE_END_OTHER             14
+#define ABILITYEFFECT_NEUTRALIZINGGAS            15
+// Special cases
 #define ABILITYEFFECT_SWITCH_IN_TERRAIN          0xFE
 #define ABILITYEFFECT_SWITCH_IN_WEATHER          0xFF
 

include/constants/battle_string_ids.h

@@ -597,8 +597,10 @@
 #define STRINGID_BUTPOKEMONCANTUSETHEMOVE             594
 #define STRINGID_BUTHOOPACANTUSEIT                    595
 #define STRINGID_BROKETHROUGHPROTECTION               596
+#define STRINGID_NEUTRALIZINGGASENTERS                597
+#define STRINGID_NEUTRALIZINGGASOVER                  598
 
-#define BATTLESTRINGS_COUNT                           597
+#define BATTLESTRINGS_COUNT                           599
 
 // The below IDs are all indexes into battle message tables,
 // used to determine which of a set of messages to print.
@@ -833,6 +835,7 @@
 #define B_MSG_SWITCHIN_SCREENCLEANER    12
 #define B_MSG_SWITCHIN_ASONE            13
 #define B_MSG_SWITCHIN_CURIOUS_MEDICINE 14
+#define B_MSG_SWITCHIN_NEUTRALIZING_GAS 15
 
 // gMentalHerbCureStringIds
 #define B_MSG_MENTALHERBCURE_INFATUATION       0

src/battle_main.c

@@ -3534,6 +3534,10 @@ static void TryDoEventsBeforeFirstTurn(void)
         }
     }
     
+    // Check neutralizing gas
+    if (AbilityBattleEffects(ABILITYEFFECT_NEUTRALIZINGGAS, 0, 0, 0, 0) != 0)
+        return;
+    
     // Check all switch in abilities happening from the fastest mon to slowest.
     while (gBattleStruct->switchInAbilitiesCounter < gBattlersCount)
     {

src/battle_message.c

@@ -723,9 +723,12 @@ static const u8 sText_PkmnRevertedToPrimal[] = _("{B_ATK_NAME_WITH_PREFIX}'s Pri
 static const u8 sText_ButPokemonCantUseTheMove[] = _("But {B_ATK_NAME_WITH_PREFIX} can't\nuse the move!");
 static const u8 sText_ButHoopaCantUseIt[] = _("But Hoopa can't use it\nthe way it is now!");
 static const u8 sText_BrokeThroughProtection[] = _("It broke through the\n{B_DEF_NAME_WITH_PREFIX}'s protection!");
-
+static const u8 sText_NeutralizingGasEnters[] = _("Neutralizing Gas filled the area!");
+static const u8 sText_NeutralizingGasOver[] = _("The effects of Neutralizing\nGas wore off!");
 const u8 *const gBattleStringsTable[BATTLESTRINGS_COUNT] =
 {
+    [STRINGID_NEUTRALIZINGGASOVER - 12] = sText_NeutralizingGasOver,
+    [STRINGID_NEUTRALIZINGGASENTERS - 12] = sText_NeutralizingGasEnters,
     [STRINGID_BROKETHROUGHPROTECTION - 12] = sText_BrokeThroughProtection,
     [STRINGID_BUTPOKEMONCANTUSETHEMOVE - 12] = sText_ButPokemonCantUseTheMove,
     [STRINGID_BUTHOOPACANTUSEIT - 12] = sText_ButHoopaCantUseIt,
@@ -1371,6 +1374,7 @@ const u16 gSwitchInAbilityStringIds[] =
     [B_MSG_SWITCHIN_SCREENCLEANER] = STRINGID_SCREENCLEANERENTERS,
     [B_MSG_SWITCHIN_ASONE] = STRINGID_ASONEENTERS,
     [B_MSG_SWITCHIN_CURIOUS_MEDICINE] = STRINGID_CURIOUSMEDICINEENTERS,
+    [B_MSG_SWITCHIN_NEUTRALIZING_GAS] = STRINGID_NEUTRALIZINGGASENTERS,
 };
 
 const u16 gMissStringIds[] =

src/battle_script_commands.c

@@ -6078,7 +6078,16 @@ static void Cmd_switchineffects(void)
     gHitMarker &= ~(HITMARKER_FAINTED(gActiveBattler));
     gSpecialStatuses[gActiveBattler].flag40 = 0;
     
-    if (!(gSideStatuses[GetBattlerSide(gActiveBattler)] & SIDE_STATUS_SPIKES_DAMAGED)
+    // Neutralizing Gas announces itself before hazards
+    if (gBattleMons[gActiveBattler].ability == ABILITY_NEUTRALIZING_GAS && gSpecialStatuses[gActiveBattler].announceNeutralizingGas == 0)
+    {
+        gBattleCommunication[MULTISTRING_CHOOSER] = B_MSG_SWITCHIN_NEUTRALIZING_GAS;
+        gSpecialStatuses[gActiveBattler].announceNeutralizingGas = TRUE;
+        gBattlerAbility = gActiveBattler;
+        BattleScriptPushCursor();
+        gBattlescriptCurrInstr = BattleScript_SwitchInAbilityMsgRet;
+    }
+    else if (!(gSideStatuses[GetBattlerSide(gActiveBattler)] & SIDE_STATUS_SPIKES_DAMAGED)
         && (gSideStatuses[GetBattlerSide(gActiveBattler)] & SIDE_STATUS_SPIKES)
         && GetBattlerAbility(gActiveBattler) != ABILITY_MAGIC_GUARD
         && IsBattlerAffectedByHazards(gActiveBattler, FALSE)
@@ -12282,6 +12291,14 @@ static void Cmd_switchoutabilities(void)
 {
     gActiveBattler = GetBattlerForBattleScript(gBattlescriptCurrInstr[1]);
     
+    if (gBattleMons[gActiveBattler].ability == ABILITY_NEUTRALIZING_GAS)
+    {
+        gBattleMons[gActiveBattler].ability = 0;
+        BattleScriptPushCursor();
+        gBattlescriptCurrInstr = BattleScript_NeutralizingGasExits;
+    }
+    else
+    {
         switch (GetBattlerAbility(gActiveBattler))
         {
         case ABILITY_NATURAL_CURE:
@@ -12301,6 +12318,7 @@ static void Cmd_switchoutabilities(void)
         
         gBattlescriptCurrInstr += 2;
     }
+}
 
 static void Cmd_jumpifhasnohp(void)
 {

src/battle_util.c

@@ -5436,6 +5436,20 @@ u8 AbilityBattleEffects(u8 caseID, u8 battler, u16 ability, u8 special, u16 move
             }
         }
         break;
+    case ABILITYEFFECT_NEUTRALIZINGGAS:
+        // for the start of battle only. The switch-in message plays in Cmd_switchineffects because it comes before the hazards
+        for (i = 0; i < gBattlersCount; i++)
+        {
+            if (gBattleMons[i].ability == ABILITY_NEUTRALIZING_GAS && !(gBattleResources->flags->flags[i] & RESOURCE_FLAG_NEUTRALIZING_GAS))
+            {
+                gBattleResources->flags->flags[i] |= RESOURCE_FLAG_NEUTRALIZING_GAS;
+                gBattlerAbility = i;
+                gBattleCommunication[MULTISTRING_CHOOSER] = B_MSG_SWITCHIN_NEUTRALIZING_GAS;
+                BattleScriptPushCursorAndCallback(BattleScript_SwitchInAbilityMsg);
+                effect++;
+            }
+        }
+        break;
     }
 
     if (effect && gLastUsedAbility != 0xFF)
@@ -5446,11 +5460,51 @@ u8 AbilityBattleEffects(u8 caseID, u8 battler, u16 ability, u8 special, u16 move
     return effect;
 }
 
+static bool32 IsNeutralizingGasBannedAbility(u32 ability)
+{
+    switch (ability)
+    {
+    case ABILITY_MULTITYPE:
+    case ABILITY_ZEN_MODE:
+    case ABILITY_STANCE_CHANGE:
+    case ABILITY_POWER_CONSTRUCT:
+    case ABILITY_SCHOOLING:
+    case ABILITY_RKS_SYSTEM:
+    case ABILITY_SHIELDS_DOWN:
+    case ABILITY_COMATOSE:
+    case ABILITY_DISGUISE:
+    case ABILITY_GULP_MISSILE:
+    case ABILITY_ICE_FACE:
+    case ABILITY_AS_ONE_ICE_RIDER:
+    case ABILITY_AS_ONE_SHADOW_RIDER:
+        return TRUE;
+    default:
+        return FALSE;
+    }
+}
+
+static bool32 IsNeutralizingGasOnField(void)
+{
+    u32 i;
+
+    for (i = 0; i < gBattlersCount; i++)
+    {
+        if (IsBattlerAlive(i) && gBattleMons[i].ability == ABILITY_NEUTRALIZING_GAS)
+            return TRUE;
+    }
+
+    return FALSE;
+}
+
 u32 GetBattlerAbility(u8 battlerId)
 {
     if (gStatuses3[battlerId] & STATUS3_GASTRO_ACID)
         return ABILITY_NONE;
-    else if ((((gBattleMons[gBattlerAttacker].ability == ABILITY_MOLD_BREAKER
+    
+    if (IsNeutralizingGasOnField() && !IsNeutralizingGasBannedAbility(gBattleMons[battlerId].ability))
+        return ABILITY_NONE;
+    
+    if ((((gBattleMons[gBattlerAttacker].ability == ABILITY_MOLD_BREAKER
             || gBattleMons[gBattlerAttacker].ability == ABILITY_TERAVOLT
             || gBattleMons[gBattlerAttacker].ability == ABILITY_TURBOBLAZE)
             && !(gStatuses3[gBattlerAttacker] & STATUS3_GASTRO_ACID))
@@ -5460,7 +5514,7 @@ u32 GetBattlerAbility(u8 battlerId)
             && gActionsByTurnOrder[gBattlerByTurnOrder[gBattlerAttacker]] == B_ACTION_USE_MOVE
             && gCurrentTurnActionNumber < gBattlersCount)
         return ABILITY_NONE;
-    else
+    
     return gBattleMons[battlerId].ability;
 }