diff --git a/include/constants/items.h b/include/constants/items.h
index d7d325376..2d186601b 100644
--- a/include/constants/items.h
+++ b/include/constants/items.h
@@ -965,7 +965,11 @@
 #define ITEM_STEEL_TERA_SHARD 790
 #define ITEM_WATER_TERA_SHARD 791
 
-#define ITEMS_COUNT 792
+#define ITEM_ADAMANT_CRYSTAL 792
+#define ITEM_GRISEOUS_CORE 793
+#define ITEM_LUSTROUS_GLOBE 794
+
+#define ITEMS_COUNT 795
 #define ITEM_FIELD_ARROW ITEMS_COUNT
 
 // A special item id associated with "Cancel"/"Exit" etc. in a list of items or decorations
diff --git a/src/data/item_icon_table.h b/src/data/item_icon_table.h
index 0dbec3f85..a0c27ea72 100644
--- a/src/data/item_icon_table.h
+++ b/src/data/item_icon_table.h
@@ -837,6 +837,9 @@ const u32 *const gItemIconTable[ITEMS_COUNT + 1][2] =
     [ITEM_ROCK_TERA_SHARD] = {gItemIcon_QuestionMark, gItemIconPalette_QuestionMark}, // {gItemIcon_RockTeraShard, gItemIconPalette_RockTeraShard},
     [ITEM_STEEL_TERA_SHARD] = {gItemIcon_QuestionMark, gItemIconPalette_QuestionMark}, // {gItemIcon_SteelTeraShard, gItemIconPalette_SteelTeraShard},
     [ITEM_WATER_TERA_SHARD] = {gItemIcon_QuestionMark, gItemIconPalette_QuestionMark}, // {gItemIcon_WaterTeraShard, gItemIconPalette_WaterTeraShard},
+    [ITEM_ADAMANT_CRYSTAL] = {gItemIcon_QuestionMark, gItemIconPalette_QuestionMark}, // {gItemIcon_AdamantCrystal, gItemIconPalette_AdamantCrystal},
+    [ITEM_GRISEOUS_CORE] = {gItemIcon_QuestionMark, gItemIconPalette_QuestionMark}, // {gItemIcon_GriseousCore, gItemIconPalette_GriseousCore},
+    [ITEM_LUSTROUS_GLOBE] = {gItemIcon_QuestionMark, gItemIconPalette_QuestionMark}, // {gItemIcon_LustrousGlobe, gItemIconPalette_LustrousGlobe},
     // Return to field arrow
     [ITEMS_COUNT] = {gItemIcon_ReturnToFieldArrow, gItemIconPalette_ReturnToFieldArrow},
 };
diff --git a/src/data/items.h b/src/data/items.h
index 982375f3e..82e41901c 100644
--- a/src/data/items.h
+++ b/src/data/items.h
@@ -10247,4 +10247,40 @@ const struct Item gItems[] =
         .type = ITEM_USE_BAG_MENU,
         .fieldUseFunc = ItemUseOutOfBattle_CannotUse,
     },
+
+    [ITEM_ADAMANT_CRYSTAL] =
+    {
+        .name = _("AdamantCrystl"),
+        .itemId = ITEM_ADAMANT_CRYSTAL,
+        .price = 0,
+        .description = sAdamantCrystalDesc,
+        .pocket = POCKET_ITEMS,
+        .type = ITEM_USE_BAG_MENU,
+        .fieldUseFunc = ItemUseOutOfBattle_CannotUse,
+        .flingPower = 60,
+    },
+
+    [ITEM_GRISEOUS_CORE] =
+    {
+        .name = _("Griseous Core"),
+        .itemId = ITEM_GRISEOUS_CORE,
+        .price = 0,
+        .description = sGriseousCoreDesc,
+        .pocket = POCKET_ITEMS,
+        .type = ITEM_USE_BAG_MENU,
+        .fieldUseFunc = ItemUseOutOfBattle_CannotUse,
+        .flingPower = 60,
+    },
+
+    [ITEM_LUSTROUS_GLOBE] =
+    {
+        .name = _("LustrousGlobe"),
+        .itemId = ITEM_LUSTROUS_GLOBE,
+        .price = 0,
+        .description = sLustrousGlobeDesc,
+        .pocket = POCKET_ITEMS,
+        .type = ITEM_USE_BAG_MENU,
+        .fieldUseFunc = ItemUseOutOfBattle_CannotUse,
+        .flingPower = 60,
+    },
 };
diff --git a/src/data/pokemon/form_change_table_pointers.h b/src/data/pokemon/form_change_table_pointers.h
index 90be7112b..62afeb2e0 100644
--- a/src/data/pokemon/form_change_table_pointers.h
+++ b/src/data/pokemon/form_change_table_pointers.h
@@ -1,6 +1,10 @@
 const struct FormChange *const gFormChangeTablePointers[NUM_SPECIES] =
 {
 #if P_GEN_4_POKEMON == TRUE
+    [SPECIES_DIALGA] = sDialgaFormChangeTable,
+    [SPECIES_DIALGA_ORIGIN] = sDialgaFormChangeTable,
+    [SPECIES_PALKIA] = sPalkiaFormChangeTable,
+    [SPECIES_PALKIA_ORIGIN] = sPalkiaFormChangeTable,
     [SPECIES_GIRATINA] = sGiratinaFormChangeTable,
     [SPECIES_GIRATINA_ORIGIN] = sGiratinaFormChangeTable,
     [SPECIES_SHAYMIN] = sShayminFormChangeTable,
diff --git a/src/data/pokemon/form_change_tables.h b/src/data/pokemon/form_change_tables.h
index 94da0add3..723bda4b2 100644
--- a/src/data/pokemon/form_change_tables.h
+++ b/src/data/pokemon/form_change_tables.h
@@ -44,9 +44,21 @@ FORM_BATTLE_END:
 #define NIGHT  2
 
 #if P_GEN_4_POKEMON == TRUE
+static const struct FormChange sDialgaFormChangeTable[] = {
+    {FORM_ITEM_HOLD, SPECIES_DIALGA, ITEM_NONE},
+    {FORM_ITEM_HOLD, SPECIES_DIALGA_ORIGIN, ITEM_ADAMANT_CRYSTAL},
+    {FORM_CHANGE_END},
+};
+
+static const struct FormChange sPalkiaFormChangeTable[] = {
+    {FORM_ITEM_HOLD, SPECIES_PALKIA, ITEM_NONE},
+    {FORM_ITEM_HOLD, SPECIES_PALKIA_ORIGIN, ITEM_LUSTROUS_GLOBE},
+    {FORM_CHANGE_END},
+};
+
 static const struct FormChange sGiratinaFormChangeTable[] = {
     {FORM_ITEM_HOLD, SPECIES_GIRATINA, ITEM_NONE},
-    {FORM_ITEM_HOLD, SPECIES_GIRATINA_ORIGIN, ITEM_GRISEOUS_ORB},
+    {FORM_ITEM_HOLD, SPECIES_GIRATINA_ORIGIN, ITEM_GRISEOUS_CORE},
     {FORM_CHANGE_END},
 };
 
diff --git a/src/data/text/item_descriptions.h b/src/data/text/item_descriptions.h
index cee413aa5..da15f001c 100644
--- a/src/data/text/item_descriptions.h
+++ b/src/data/text/item_descriptions.h
@@ -3877,3 +3877,18 @@ static const u8 sTeraShardDesc[] = _(
     "These shards may\n"
     "form when a Tera\n"
     "Pokémon faints.");
+
+static const u8 sAdamantCrystalDesc[] = _(
+    "A large, glowing gem\n"
+    "that lets Dialga\n"
+    "change form.");
+
+static const u8 sGriseousCoreDesc[] = _(
+    "A large, glowing gem\n"
+    "that lets Giratina\n"
+    "change form.");
+
+static const u8 sLustrousGlobeDesc[] = _(
+    "A large, glowing gem\n"
+    "that lets Palkia\n"
+    "change form.");