diff --git a/Makefile b/Makefile
index aae215c587..facc0a8d83 100644
--- a/Makefile
+++ b/Makefile
@@ -372,6 +372,13 @@ ifneq ($(NODEP),1)
 -include $(addprefix $(OBJ_DIR)/,$(C_SRCS:.c=.d))
 endif
 
+$(TEST_BUILDDIR)/%.o: $(TEST_SUBDIR)/%.c
+	@echo "$(CC1) <flags> -o $@ $<"
+	@$(CPP) $(CPPFLAGS) $< | $(PREPROC) -i $< charmap.txt | $(CC1) $(CFLAGS) -o - - | cat - <(echo -e ".text\n\t.align\t2, 0") | $(AS) $(ASFLAGS) -o $@ -
+
+$(TEST_BUILDDIR)/%.d: $(TEST_SUBDIR)/%.c
+	$(SCANINC) -M $@ $(INCLUDE_SCANINC_ARGS) -I tools/agbcc/include $<
+
 $(ASM_BUILDDIR)/%.o: $(ASM_SUBDIR)/%.s
 	$(AS) $(ASFLAGS) -o $@ $<
 
@@ -415,14 +422,6 @@ $(OBJ_DIR)/sym_ewram.ld: sym_ewram.txt
 $(DATA_SRC_SUBDIR)/pokemon/teachable_learnsets.h: $(DATA_ASM_BUILDDIR)/event_scripts.o
 	python3 $(TOOLS_DIR)/learnset_helpers/teachable.py
 
-# NOTE: Based on C_DEP above, but without NODEP and KEEP_TEMPS handling.
-define TEST_DEP
-$1: $2 $$(shell $(SCANINC) -I include -I $(TOOLS_DIR)/agbcc/include $2)
-	@echo "$$(CC1) <flags> -o $$@ $$<"
-	@$$(CPP) $$(CPPFLAGS) $$< | $$(PREPROC) -i $$< charmap.txt | $$(CC1) $$(CFLAGS) -o - - | cat - <(echo -e ".text\n\t.align\t2, 0") | $$(AS) $$(ASFLAGS) -o $$@ -
-endef
-$(foreach src, $(TEST_SRCS), $(eval $(call TEST_DEP,$(patsubst $(TEST_SUBDIR)/%.c,$(TEST_BUILDDIR)/%.o,$(src)),$(src),$(patsubst $(TEST_SUBDIR)/%.c,%,$(src)))))
-
 # Linker script
 LD_SCRIPT := ld_script_modern.ld
 LD_SCRIPT_DEPS :=
diff --git a/src/battle_gfx_sfx_util.c b/src/battle_gfx_sfx_util.c
index 0aa5e1b95b..3729a4f73f 100644
--- a/src/battle_gfx_sfx_util.c
+++ b/src/battle_gfx_sfx_util.c
@@ -931,7 +931,7 @@ void HandleSpeciesGfxDataChange(u8 battlerAtk, u8 battlerDef, bool32 megaEvo, bo
 
         if (GetBattlerSide(battlerAtk) == B_SIDE_PLAYER)
         {
-            if (B_TRANSFORM_SHINY >= GEN_4 && trackEnemyPersonality)
+            if (B_TRANSFORM_SHINY >= GEN_4 && trackEnemyPersonality && !megaEvo)
             {
                 personalityValue = GetMonData(&gEnemyParty[gBattlerPartyIndexes[battlerDef]], MON_DATA_PERSONALITY);
                 isShiny = GetMonData(&gEnemyParty[gBattlerPartyIndexes[battlerDef]], MON_DATA_IS_SHINY);
@@ -949,7 +949,7 @@ void HandleSpeciesGfxDataChange(u8 battlerAtk, u8 battlerDef, bool32 megaEvo, bo
         }
         else
         {
-            if (B_TRANSFORM_SHINY >= GEN_4 && trackEnemyPersonality)
+            if (B_TRANSFORM_SHINY >= GEN_4 && trackEnemyPersonality && !megaEvo)
             {
                 personalityValue = GetMonData(&gPlayerParty[gBattlerPartyIndexes[battlerDef]], MON_DATA_PERSONALITY);
                 isShiny = GetMonData(&gPlayerParty[gBattlerPartyIndexes[battlerDef]], MON_DATA_IS_SHINY);
diff --git a/src/battle_util.c b/src/battle_util.c
index 1dd7b41938..0b4496464b 100644
--- a/src/battle_util.c
+++ b/src/battle_util.c
@@ -2297,14 +2297,14 @@ s32 GetDrainedBigRootHp(u32 battler, s32 hp)
     return hp * -1;
 }
 
-#define MAGIC_GUARD_CHECK \
-if (ability == ABILITY_MAGIC_GUARD) \
-{\
-    RecordAbilityBattle(battler, ability);\
-    gBattleStruct->turnEffectsTracker++;\
-            break;\
-}
+static inline bool32 IsBattlerProtectedByMagicGuard(u32 battler, u32 ability)
+{
+    if (ability != ABILITY_MAGIC_GUARD)
+        return FALSE;
 
+    RecordAbilityBattle(battler, ability);
+    return TRUE;
+}
 
 u8 DoBattlerEndTurnEffects(void)
 {
@@ -2432,10 +2432,9 @@ u8 DoBattlerEndTurnEffects(void)
         case ENDTURN_LEECH_SEED:  // leech seed
             if ((gStatuses3[battler] & STATUS3_LEECHSEED)
              && IsBattlerAlive(gStatuses3[battler] & STATUS3_LEECHSEED_BATTLER)
-             && IsBattlerAlive(battler))
+             && IsBattlerAlive(battler)
+             && !IsBattlerProtectedByMagicGuard(battler, ability))
             {
-                MAGIC_GUARD_CHECK;
-
                 gBattlerTarget = gStatuses3[battler] & STATUS3_LEECHSEED_BATTLER; // Notice gBattlerTarget is actually the HP receiver.
                 gBattleMoveDamage = GetNonDynamaxMaxHP(battler) / 8;
                 if (gBattleMoveDamage == 0)
@@ -2449,10 +2448,9 @@ u8 DoBattlerEndTurnEffects(void)
             break;
         case ENDTURN_POISON:  // poison
             if ((gBattleMons[battler].status1 & STATUS1_POISON)
-                && IsBattlerAlive(battler))
+             && IsBattlerAlive(battler)
+             && !IsBattlerProtectedByMagicGuard(battler, ability))
             {
-                MAGIC_GUARD_CHECK;
-
                 if (ability == ABILITY_POISON_HEAL)
                 {
                     if (!BATTLER_MAX_HP(battler) && !(gStatuses3[battler] & STATUS3_HEAL_BLOCK))
@@ -2478,10 +2476,9 @@ u8 DoBattlerEndTurnEffects(void)
             break;
         case ENDTURN_BAD_POISON:  // toxic poison
             if ((gBattleMons[battler].status1 & STATUS1_TOXIC_POISON)
-                && IsBattlerAlive(battler))
+              && IsBattlerAlive(battler)
+              && !IsBattlerProtectedByMagicGuard(battler, ability))
             {
-                MAGIC_GUARD_CHECK;
-
                 if (ability == ABILITY_POISON_HEAL)
                 {
                     if (!BATTLER_MAX_HP(battler) && !(gStatuses3[battler] & STATUS3_HEAL_BLOCK))
@@ -2510,9 +2507,9 @@ u8 DoBattlerEndTurnEffects(void)
             break;
         case ENDTURN_BURN:  // burn
             if ((gBattleMons[battler].status1 & STATUS1_BURN)
-                && IsBattlerAlive(battler))
+             && IsBattlerAlive(battler)
+             && !IsBattlerProtectedByMagicGuard(battler, ability))
             {
-                MAGIC_GUARD_CHECK;
                 gBattleMoveDamage = GetNonDynamaxMaxHP(battler) / (B_BURN_DAMAGE >= GEN_7 ? 16 : 8);
                 if (ability == ABILITY_HEATPROOF)
                 {
@@ -2529,9 +2526,9 @@ u8 DoBattlerEndTurnEffects(void)
             break;
         case ENDTURN_FROSTBITE:  // burn
             if ((gBattleMons[battler].status1 & STATUS1_FROSTBITE)
-                && IsBattlerAlive(battler))
+             && IsBattlerAlive(battler)
+             && !IsBattlerProtectedByMagicGuard(battler, ability))
             {
-                MAGIC_GUARD_CHECK;
                 gBattleMoveDamage = GetNonDynamaxMaxHP(battler) / (B_BURN_DAMAGE >= GEN_7 ? 16 : 8);
                 if (gBattleMoveDamage == 0)
                     gBattleMoveDamage = 1;
@@ -2542,9 +2539,9 @@ u8 DoBattlerEndTurnEffects(void)
             break;
         case ENDTURN_NIGHTMARES:  // spooky nightmares
             if ((gBattleMons[battler].status2 & STATUS2_NIGHTMARE)
-                && IsBattlerAlive(battler))
+             && IsBattlerAlive(battler)
+             && !IsBattlerProtectedByMagicGuard(battler, ability))
             {
-                MAGIC_GUARD_CHECK;
                 // R/S does not perform this sleep check, which causes the nightmare effect to
                 // persist even after the affected Pokémon has been awakened by Shed Skin.
                 if (gBattleMons[battler].status1 & STATUS1_SLEEP)
@@ -2564,9 +2561,9 @@ u8 DoBattlerEndTurnEffects(void)
             break;
         case ENDTURN_CURSE:  // curse
             if ((gBattleMons[battler].status2 & STATUS2_CURSED)
-                && IsBattlerAlive(battler))
+             && IsBattlerAlive(battler)
+             && !IsBattlerProtectedByMagicGuard(battler, ability))
             {
-                MAGIC_GUARD_CHECK;
                 gBattleMoveDamage = GetNonDynamaxMaxHP(battler) / 4;
                 if (gBattleMoveDamage == 0)
                     gBattleMoveDamage = 1;
@@ -2580,7 +2577,11 @@ u8 DoBattlerEndTurnEffects(void)
             {
                 if (--gDisableStructs[battler].wrapTurns != 0)  // damaged by wrap
                 {
-                    MAGIC_GUARD_CHECK;
+                    if (IsBattlerProtectedByMagicGuard(battler, ability))
+                    {
+                        gBattleStruct->turnEffectsTracker++;
+                        break;
+                    }
 
                     gBattleScripting.animArg1 = gBattleStruct->wrappedMove[battler];
                     gBattleScripting.animArg2 = gBattleStruct->wrappedMove[battler] >> 8;
@@ -2884,7 +2885,9 @@ u8 DoBattlerEndTurnEffects(void)
             gBattleStruct->turnEffectsTracker++;
             break;
         case ENDTURN_SALT_CURE:
-            if (gStatuses4[battler] & STATUS4_SALT_CURE && IsBattlerAlive(battler))
+            if (gStatuses4[battler] & STATUS4_SALT_CURE
+             && IsBattlerAlive(battler)
+             && !IsBattlerProtectedByMagicGuard(battler, ability))
             {
                 gBattlerTarget = battler;
                 if (IS_BATTLER_OF_TYPE(gBattlerTarget, TYPE_STEEL) || IS_BATTLER_OF_TYPE(gBattlerTarget, TYPE_WATER))
diff --git a/test/battle/move_effect/fixed_damage_arg.c b/test/battle/move_effect/fixed_damage_arg.c
new file mode 100644
index 0000000000..484601be05
--- /dev/null
+++ b/test/battle/move_effect/fixed_damage_arg.c
@@ -0,0 +1,41 @@
+#include "global.h"
+#include "test/battle.h"
+
+ASSUMPTIONS
+{
+    ASSUME(gMovesInfo[MOVE_SONIC_BOOM].effect == EFFECT_FIXED_DAMAGE_ARG);
+}
+
+SINGLE_BATTLE_TEST("Sonic Boom deals fixed damage", s16 damage)
+{
+    u16 mon;
+    PARAMETRIZE { mon = SPECIES_RATTATA; }
+    PARAMETRIZE { mon = SPECIES_ARON; }
+    
+    GIVEN {
+        ASSUME(gMovesInfo[MOVE_SONIC_BOOM].argument == 20);
+        PLAYER(SPECIES_WOBBUFFET);
+        OPPONENT(mon);
+    } WHEN {
+        TURN { MOVE(player, MOVE_SONIC_BOOM); }
+    } SCENE {
+        ANIMATION(ANIM_TYPE_MOVE, MOVE_SONIC_BOOM, player);
+        HP_BAR(opponent, captureDamage: &results[i].damage);
+    } FINALLY {
+        EXPECT(results[0].damage == 20);
+        EXPECT(results[1].damage == 20);
+    }
+}
+
+SINGLE_BATTLE_TEST("Sonic Boom doesn't affect ghost types")
+{
+    GIVEN {
+        PLAYER(SPECIES_WOBBUFFET);
+        OPPONENT(SPECIES_GASTLY);
+    } WHEN {
+        TURN { MOVE(player, MOVE_SONIC_BOOM); }
+    } SCENE {
+        NOT ANIMATION(ANIM_TYPE_MOVE, MOVE_SONIC_BOOM, player);
+        MESSAGE("It doesn't affect the opposing Gastly…");
+    }
+}
diff --git a/test/battle/move_effect/salt_cure.c b/test/battle/move_effect/salt_cure.c
index 006a55d642..495a7e8c80 100644
--- a/test/battle/move_effect/salt_cure.c
+++ b/test/battle/move_effect/salt_cure.c
@@ -99,3 +99,21 @@ SINGLE_BATTLE_TEST("Salt Cure does not get applied if hitting a Substitute")
         NOT MESSAGE("The opposing Wobbuffet is being salt cured!");
     }
 }
+
+SINGLE_BATTLE_TEST("Salt Cure residual damage does not inflict any damage against Magic Guard")
+{
+    GIVEN {
+        PLAYER(SPECIES_WOBBUFFET);
+        OPPONENT(SPECIES_CLEFABLE) { Ability(ABILITY_MAGIC_GUARD); };
+    } WHEN {
+        TURN { MOVE(player, MOVE_SALT_CURE); }
+    } SCENE {
+        ANIMATION(ANIM_TYPE_MOVE, MOVE_SALT_CURE, player);
+        HP_BAR(opponent);
+        NONE_OF {
+            ANIMATION(ANIM_TYPE_GENERAL, B_ANIM_SALT_CURE_DAMAGE, opponent);
+            HP_BAR(opponent);
+            MESSAGE("The opposing Clefable is hurt by Salt Cure!");
+        }
+    }
+}
diff --git a/test/battle/terrain/starting_terrain.c b/test/battle/terrain/starting_terrain.c
index e505dbd185..ab31bbbb96 100644
--- a/test/battle/terrain/starting_terrain.c
+++ b/test/battle/terrain/starting_terrain.c
@@ -67,7 +67,7 @@ SINGLE_BATTLE_TEST("Terrain started after the one which started the battle lasts
     VarSet(B_VAR_STARTING_STATUS_TIMER, 0);
 
     GIVEN {
-        PLAYER(SPECIES_WOBBUFFET) { Ability(viaMove == TRUE ? ABILITY_SHADOW_TAG : ABILITY_GRASSY_SURGE); }
+        PLAYER(SPECIES_TAPU_BULU) { Ability(viaMove == TRUE ? ABILITY_TELEPATHY : ABILITY_GRASSY_SURGE); }
         OPPONENT(SPECIES_WOBBUFFET);
     } WHEN {
         // More than 5 turns
@@ -84,7 +84,7 @@ SINGLE_BATTLE_TEST("Terrain started after the one which started the battle lasts
         ANIMATION(ANIM_TYPE_GENERAL, B_ANIM_RESTORE_BG);
         // Player uses Grassy Terrain
         if (viaMove) {
-            MESSAGE("Wobbuffet used GrssyTerrain!");
+            MESSAGE("Tapu Bulu used Grassy Terrain!");
             ANIMATION(ANIM_TYPE_MOVE, MOVE_GRASSY_TERRAIN, player);
             MESSAGE("Grass grew to cover the battlefield!");
         } else {
@@ -94,13 +94,13 @@ SINGLE_BATTLE_TEST("Terrain started after the one which started the battle lasts
         }
 
         // 5 turns
-        MESSAGE("Wobbuffet used Celebrate!");
+        MESSAGE("Tapu Bulu used Celebrate!");
         MESSAGE("The opposing Wobbuffet used Celebrate!");
 
-        MESSAGE("Wobbuffet used Celebrate!");
+        MESSAGE("Tapu Bulu used Celebrate!");
         MESSAGE("The opposing Wobbuffet used Celebrate!");
 
-        MESSAGE("Wobbuffet used Celebrate!");
+        MESSAGE("Tapu Bulu used Celebrate!");
         MESSAGE("The opposing Wobbuffet used Celebrate!");
 
         MESSAGE("The grass disappeared from the battlefield.");
diff --git a/tools/mgba-rom-test-hydra/Makefile b/tools/mgba-rom-test-hydra/Makefile
index f93f991d9b..ef0523adc9 100644
--- a/tools/mgba-rom-test-hydra/Makefile
+++ b/tools/mgba-rom-test-hydra/Makefile
@@ -12,7 +12,7 @@ all: mgba-rom-test-hydra$(EXE)
 	@:
 
 mgba-rom-test-hydra$(EXE): $(SRCS)
-	$(CC) $(SRCS) -o $@ -lm $(LDFLAGS)
+	$(CC) $(SRCS) -Werror=implicit-function-declaration -o $@ -lm $(LDFLAGS)
 
 clean:
 	$(RM) mgba-rom-test-hydra$(EXE)
diff --git a/tools/mgba-rom-test-hydra/main.c b/tools/mgba-rom-test-hydra/main.c
index 841b7328e5..d4c0f4e080 100644
--- a/tools/mgba-rom-test-hydra/main.c
+++ b/tools/mgba-rom-test-hydra/main.c
@@ -106,6 +106,28 @@ static const struct Symbol *lookup_address(uint32_t address)
     return NULL;
 }
 
+#ifndef _GNU_SOURCE
+// Very naive implementation of 'memmem' for systems which don't make it
+// available by default.
+void *memmem(const void *haystack, size_t haystacklen, const void *needle, size_t needlelen)
+{
+    const char *haystack_ = haystack;
+    const char *needle_ = needle;
+    for (size_t i = 0; i < haystacklen - needlelen; i++)
+    {
+        size_t j;
+        for (j = 0; j < needlelen; j++)
+        {
+            if (haystack_[i+j] != needle_[j])
+                break;
+        }
+        if (j == needlelen)
+            return (void *)&haystack_[i];
+    }
+    return NULL;
+}
+#endif
+
 // Similar to 'fwrite(buffer, 1, size, f)' except that anything which
 // looks like the output of '%p' (i.e. '<0x\d{7}>') is translated into
 // the name of a symbol (if it represents one).