diff --git a/include/config/battle.h b/include/config/battle.h
index 8ef347cdcd..478210101e 100644
--- a/include/config/battle.h
+++ b/include/config/battle.h
@@ -186,6 +186,7 @@
 #define B_SAFARI_BALL_MODIFIER      GEN_LATEST // In Gen8+, Safari Ball's catch multiplier was reduced from x1.5 to x1.
 #define B_FRIEND_BALL_MODIFIER      GEN_LATEST // In Gen8+, Friend Ball's friendship boost was reduced from 200 to 150.
 #define B_SERENE_GRACE_BOOST        GEN_LATEST // In Gen5+, Serene Grace boosts the added flinch chance of King's Rock and Razor Fang.
+#define B_IRON_BALL                 GEN_LATEST // In Gen5+, Flying-type Pokemon holding Iron Ball take x1 damage from Ground-type moves regardless of their other types, except during Inverse Battles or if the Pokemon is grounded by any other effect.
 
 // Flag settings
 // To use the following features in scripting, replace the 0s with the flag ID you're assigning it to.
diff --git a/src/battle_util.c b/src/battle_util.c
index afa9b5b94a..ccd4d6fb2d 100644
--- a/src/battle_util.c
+++ b/src/battle_util.c
@@ -8816,12 +8816,24 @@ bool32 IsBattlerProtected(u32 battlerAtk, u32 battlerDef, u32 move)
     return isProtected;
 }
 
-// Only called directly when calculating damage type effectiveness
-static bool32 IsBattlerGroundedInverseCheck(u32 battler, bool32 considerInverse)
+enum InverseBattleCheck
+{
+    INVERSE_BATTLE,
+    NOT_INVERSE_BATTLE
+};
+
+enum IronBallCheck
+{
+    CHECK_IRON_BALL,
+    IGNORE_IRON_BALL
+};
+
+// Only called directly when calculating damage type effectiveness, and Iron Ball's type effectiveness mechanics
+static bool32 IsBattlerGroundedInverseCheck(u32 battler, enum InverseBattleCheck checkInverse, enum IronBallCheck checkIronBall)
 {
     u32 holdEffect = GetBattlerHoldEffect(battler, TRUE);
 
-    if (holdEffect == HOLD_EFFECT_IRON_BALL)
+    if (!(checkIronBall == IGNORE_IRON_BALL) && holdEffect == HOLD_EFFECT_IRON_BALL)
         return TRUE;
     if (gFieldStatuses & STATUS_FIELD_GRAVITY)
         return TRUE;
@@ -8837,14 +8849,14 @@ static bool32 IsBattlerGroundedInverseCheck(u32 battler, bool32 considerInverse)
         return FALSE;
     if ((AI_DATA->aiCalcInProgress ? AI_DATA->abilities[battler] : GetBattlerAbility(battler)) == ABILITY_LEVITATE)
         return FALSE;
-    if (IS_BATTLER_OF_TYPE(battler, TYPE_FLYING) && (!considerInverse || !FlagGet(B_FLAG_INVERSE_BATTLE)))
+    if (IS_BATTLER_OF_TYPE(battler, TYPE_FLYING) && (!(checkInverse == INVERSE_BATTLE) || !FlagGet(B_FLAG_INVERSE_BATTLE)))
         return FALSE;
     return TRUE;
 }
 
 bool32 IsBattlerGrounded(u32 battler)
 {
-    return IsBattlerGroundedInverseCheck(battler, FALSE);
+    return IsBattlerGroundedInverseCheck(battler, NOT_INVERSE_BATTLE, CHECK_IRON_BALL);
 }
 
 u32 GetMoveSlot(u16 *moves, u32 move)
@@ -10685,7 +10697,7 @@ static inline uq4_12_t CalcTypeEffectivenessMultiplierInternal(u32 move, u32 mov
         if (B_GLARE_GHOST < GEN_4 && move == MOVE_GLARE && IS_BATTLER_OF_TYPE(battlerDef, TYPE_GHOST))
             modifier = UQ_4_12(0.0);
     }
-    else if (moveType == TYPE_GROUND && !IsBattlerGroundedInverseCheck(battlerDef, TRUE) && !(MoveIgnoresTypeIfFlyingAndUngrounded(move)))
+    else if (moveType == TYPE_GROUND && !IsBattlerGroundedInverseCheck(battlerDef, INVERSE_BATTLE, CHECK_IRON_BALL) && !(MoveIgnoresTypeIfFlyingAndUngrounded(move)))
     {
         modifier = UQ_4_12(0.0);
         if (recordAbilities && defAbility == ABILITY_LEVITATE)
@@ -10710,6 +10722,17 @@ static inline uq4_12_t CalcTypeEffectivenessMultiplierInternal(u32 move, u32 mov
         modifier = UQ_4_12(1.0);
     }
 
+    // Iron Ball ignores type modifiers for flying-type mons if it is the only source of grounding
+    if (B_IRON_BALL >= GEN_5
+        && moveType == TYPE_GROUND
+        && IS_BATTLER_OF_TYPE(battlerDef, TYPE_FLYING)
+        && GetBattlerHoldEffect(battlerDef, TRUE) == HOLD_EFFECT_IRON_BALL
+        && !IsBattlerGroundedInverseCheck(battlerDef, NOT_INVERSE_BATTLE, IGNORE_IRON_BALL)
+        && !FlagGet(B_FLAG_INVERSE_BATTLE))
+    {
+        modifier = UQ_4_12(1.0);
+    }
+
     if (((defAbility == ABILITY_WONDER_GUARD && modifier <= UQ_4_12(1.0))
         || (defAbility == ABILITY_TELEPATHY && battlerDef == BATTLE_PARTNER(battlerAtk)))
         && GetMovePower(move) != 0)
diff --git a/test/battle/hold_effect/iron_ball.c b/test/battle/hold_effect/iron_ball.c
new file mode 100644
index 0000000000..134c47d9af
--- /dev/null
+++ b/test/battle/hold_effect/iron_ball.c
@@ -0,0 +1,22 @@
+#include "global.h"
+#include "test/battle.h"
+
+ASSUMPTIONS{
+    ASSUME(gItemsInfo[ITEM_IRON_BALL].holdEffect == HOLD_EFFECT_IRON_BALL);
+}
+
+SINGLE_BATTLE_TEST("Ground-type moves do neutral damage to non-grounded Flying types holding Iron Ball regardless of other typings") //gen5+ only
+{
+    ASSUME(B_IRON_BALL >= GEN_5);
+    GIVEN {
+        PLAYER(SPECIES_WOBBUFFET);
+        OPPONENT(SPECIES_SKARMORY) { Item(ITEM_IRON_BALL); };
+    } WHEN {
+        TURN { MOVE(player, MOVE_EARTHQUAKE); };
+    } SCENE {
+        ANIMATION(ANIM_TYPE_MOVE, MOVE_EARTHQUAKE, player);
+        NONE_OF {
+            MESSAGE("It's super effective!");
+        }
+    }
+}