diff --git a/asm/macros/battle_script.inc b/asm/macros/battle_script.inc
index 9fa3fe0c3..b5d21abc4 100644
--- a/asm/macros/battle_script.inc
+++ b/asm/macros/battle_script.inc
@@ -1726,6 +1726,14 @@
 	.4byte \ptr
 	.endm
 
+	.macro photongeysercheck
+	various BS_ATTACKER, VARIOUS_PHOTON_GEYSER_CHECK
+	.endm
+
+	.macro shellsidearmcheck
+	various BS_ATTACKER, VARIOUS_SHELL_SIDE_ARM_CHECK
+	.endm
+
 	.macro trysetfairylock ptr:req
 	various BS_ATTACKER, VARIOUS_TRY_FAIRY_LOCK
 	.4byte \ptr
diff --git a/data/battle_scripts_1.s b/data/battle_scripts_1.s
index 77eddc8ab..544583961 100644
--- a/data/battle_scripts_1.s
+++ b/data/battle_scripts_1.s
@@ -367,6 +367,14 @@ gBattleScriptsForMoveEffects:: @ 82D86A8
 	.4byte BattleScript_EffectFairyLock
 	.4byte BattleScript_EffectAllySwitch
 	.4byte BattleScript_EffectSleepHit
+	.4byte BattleScript_EffectPhotonGeyser
+	.4byte BattleScript_EffectShellSideArm
+
+BattleScript_EffectShellSideArm:
+	shellsidearmcheck
+
+BattleScript_EffectPhotonGeyser:
+	photongeysercheck
 
 BattleScript_EffectSleepHit:
 	setmoveeffect MOVE_EFFECT_SLEEP
diff --git a/include/battle.h b/include/battle.h
index 82a917538..2195e0a21 100644
--- a/include/battle.h
+++ b/include/battle.h
@@ -858,4 +858,6 @@ extern u8 gBattleControllerData[MAX_BATTLERS_COUNT];
 extern bool8 gHasFetchedBall;
 extern u8 gLastUsedBall;
 
+extern bool8 gSwapDamageCategory; // Photon Geyser, Shell Side Arm, Light That Burns the Sky
+
 #endif // GUARD_BATTLE_H
diff --git a/include/constants/battle_move_effects.h b/include/constants/battle_move_effects.h
index 74418d2c7..b9cf92854 100644
--- a/include/constants/battle_move_effects.h
+++ b/include/constants/battle_move_effects.h
@@ -351,7 +351,9 @@
 #define EFFECT_FAIRY_LOCK 345
 #define EFFECT_ALLY_SWITCH 346
 #define EFFECT_SLEEP_HIT 347 // Relic Song
+#define EFFECT_PHOTON_GEYSER 348
+#define EFFECT_SHELL_SIDE_ARM 349
 
-#define NUM_BATTLE_MOVE_EFFECTS 348
+#define NUM_BATTLE_MOVE_EFFECTS 350
 
 #endif  // GUARD_CONSTANTS_BATTLE_MOVE_EFFECTS_H
diff --git a/include/constants/battle_script_commands.h b/include/constants/battle_script_commands.h
index faaf8f17e..28ba1a5d4 100644
--- a/include/constants/battle_script_commands.h
+++ b/include/constants/battle_script_commands.h
@@ -173,6 +173,8 @@
 #define VARIOUS_DESTROY_ABILITY_POPUP           102
 #define VARIOUS_TOTEM_BOOST                     103
 #define VARIOUS_TRY_ACTIVATE_GRIM_NEIGH         104
+#define VARIOUS_PHOTON_GEYSER_CHECK          105
+#define VARIOUS_SHELL_SIDE_ARM_CHECK          106
 
 // Cmd_manipulatedamage
 #define DMG_CHANGE_SIGN            0
diff --git a/src/battle_main.c b/src/battle_main.c
index 77470246f..739d33a3e 100644
--- a/src/battle_main.c
+++ b/src/battle_main.c
@@ -229,6 +229,7 @@ EWRAM_DATA u16 gPartnerSpriteId = 0;
 EWRAM_DATA struct TotemBoost gTotemBoosts[MAX_BATTLERS_COUNT] = {0};
 EWRAM_DATA bool8 gHasFetchedBall = FALSE;
 EWRAM_DATA u8 gLastUsedBall = 0;
+EWRAM_DATA bool8 gSwapDamageCategory = FALSE; // Photon Geyser, Shell Side Arm, Light That Burns the Sky
 
 // IWRAM common vars
 void (*gPreBattleCallback1)(void);
@@ -2928,6 +2929,8 @@ static void BattleStartClearSetData(void)
     gBattleStruct->arenaLostOpponentMons = 0;
 
     gBattleStruct->mega.triggerSpriteId = 0xFF;
+
+    gSwapDamageCategory = FALSE; // Photon Geyser, Shell Side Arm, Light That Burns the Sky
 }
 
 void SwitchInClearSetData(void)
diff --git a/src/battle_script_commands.c b/src/battle_script_commands.c
index fc0eedcbc..2a761e5c6 100644
--- a/src/battle_script_commands.c
+++ b/src/battle_script_commands.c
@@ -7126,6 +7126,55 @@ static void Cmd_various(void)
 
     switch (gBattlescriptCurrInstr[2])
     {
+    case VARIOUS_PHOTON_GEYSER_CHECK:
+    {
+        u32 attStat = gBattleMons[gActiveBattler].attack;
+        u8 atkStage = gBattleMons[gActiveBattler].statStages[STAT_ATK];
+        u32 spaStat = gBattleMons[gActiveBattler].spAttack;
+
+        attStat *= gStatStageRatios[atkStage][0];
+        attStat /= gStatStageRatios[atkStage][1];
+
+        atkStage = gBattleMons[gActiveBattler].statStages[STAT_SPATK];
+        spaStat *= gStatStageRatios[atkStage][0];
+        spaStat /= gStatStageRatios[atkStage][1];
+
+        if (attStat > spaStat)
+            gSwapDamageCategory = TRUE;
+    }
+    case VARIOUS_SHELL_SIDE_ARM_CHECK: // according to DaWoblefet, 0% chance GameFreak actually checks this way, but this is the only functional explanation at the moment
+    {
+        u32 attStat = gBattleMons[gBattlerAttacker].attack;
+        u8 atkStage = gBattleMons[gBattlerAttacker].statStages[STAT_ATK];
+        u32 attStatDef = gBattleMons[gBattlerTarget].attack;
+        u32 physical;
+
+        u32 spaStat = gBattleMons[gBattlerAttacker].spAttack;
+        u32 spaStatDef = gBattleMons[gBattlerTarget].spAttack;
+        u32 special;
+
+        attStat *= gStatStageRatios[atkStage][0];
+        attStat /= gStatStageRatios[atkStage][1];
+
+        atkStage = gBattleMons[gBattlerTarget].statStages[STAT_ATK];
+        attStatDef *= gStatStageRatios[atkStage][0];
+        attStatDef /= gStatStageRatios[atkStage][1];
+
+        physical = ((((2 * gBattleMons[gBattlerAttacker].level / 5 + 2) * 90 * attStat) / attStatDef) / 50);
+
+        atkStage = gBattleMons[gBattlerAttacker].statStages[STAT_SPATK];
+        spaStat *= gStatStageRatios[atkStage][0];
+        spaStat /= gStatStageRatios[atkStage][1];
+
+        atkStage = gBattleMons[gBattlerTarget].statStages[STAT_SPATK];
+        spaStatDef *= gStatStageRatios[atkStage][0];
+        spaStatDef /= gStatStageRatios[atkStage][1];
+
+        special = ((((2 * gBattleMons[gBattlerAttacker].level / 5 + 2) * 90 * spaStat) / spaStatDef) / 50);
+
+        if (((physical > special) || (physical == special && (Random() % 2) == 0)))
+            gSwapDamageCategory = TRUE;
+    }
     // Roar will fail in a double wild battle when used by the player against one of the two alive wild mons.
     // Also when an opposing wild mon uses it againt its partner.
     case VARIOUS_JUMP_IF_ROAR_FAILS:
diff --git a/src/battle_util.c b/src/battle_util.c
index 07c150066..e657a4e96 100644
--- a/src/battle_util.c
+++ b/src/battle_util.c
@@ -8367,8 +8367,11 @@ bool8 ShouldGetStatBadgeBoost(u16 badgeFlag, u8 battlerId)
 u8 GetBattleMoveSplit(u32 moveId)
 {
     if (IS_MOVE_STATUS(moveId) || B_PHYSICAL_SPECIAL_SPLIT >= GEN_4)
-        return gBattleMoves[moveId].split;
-    else if (gBattleMoves[moveId].type < TYPE_MYSTERY)
+        if (gSwapDamageCategory == TRUE)  // Photon Geyser, Shell Side Arm, Light That Burns the Sky
+            return SPLIT_PHYSICAL;
+        else
+            return gBattleMoves[moveId].split;
+    else if (gBattleMoves[moveId].type < TYPE_MYSTERY || gSwapDamageCategory == TRUE) // Photon Geyser, Shell Side Arm, Light That Burns the Sky
         return SPLIT_PHYSICAL;
     else
         return SPLIT_SPECIAL;
diff --git a/src/data/battle_moves.h b/src/data/battle_moves.h
index 61050e44f..0e27bb588 100644
--- a/src/data/battle_moves.h
+++ b/src/data/battle_moves.h
@@ -10343,15 +10343,15 @@ const struct BattleMove gBattleMoves[MOVES_COUNT] =
 
     [MOVE_PHOTON_GEYSER] =
     {
-        .effect = EFFECT_PLACEHOLDER, // Needs a custom move effect
+        .effect = EFFECT_PHOTON_GEYSER,
         .power = 100,
         .type = TYPE_PSYCHIC,
         .accuracy = 100,
         .pp = 5,
-        .secondaryEffectChance = 0,
+        .secondaryEffectChance = 100,
         .target = MOVE_TARGET_FOES_AND_ALLY,
         .priority = 0,
-        .flags = FLAG_PROTECT_AFFECTED | FLAG_MIRROR_MOVE_AFFECTED | FLAG_KINGS_ROCK_AFFECTED,
+        .flags = FLAG_PROTECT_AFFECTED | FLAG_MIRROR_MOVE_AFFECTED | FLAG_KINGS_ROCK_AFFECTED | FLAG_TARGET_ABILITY_IGNORED,
         .split = SPLIT_SPECIAL,
     },
 
@@ -11178,12 +11178,12 @@ const struct BattleMove gBattleMoves[MOVES_COUNT] =
 
     [MOVE_SHELL_SIDE_ARM] =
     {
-        .effect = EFFECT_PLACEHOLDER,   //TODO
+        .effect = EFFECT_SHELL_SIDE_ARM,
         .power = 90,
         .type = TYPE_POISON,
         .accuracy = 100,
         .pp = 10,
-        .secondaryEffectChance = 0,
+        .secondaryEffectChance = 100,
         .target = MOVE_TARGET_SELECTED,
         .priority = 0,
         .flags = FLAG_PROTECT_AFFECTED | FLAG_MIRROR_MOVE_AFFECTED | FLAG_KINGS_ROCK_AFFECTED,