combine "unused" field into tile buffer

src/pokemon_storage_system.c

@@ -550,8 +550,7 @@ struct PokemonStorageSystemData
     u16 *displayMonTilePtr;
     struct Sprite *displayMonSprite;
     u16 displayMonPalBuffer[0x40];
-    u8 tileBuffer[0x800];
+    u8 tileBuffer[MON_PIC_SIZE * 4]; // 4x the size of a 'Mon sprite to account for Castform
-    u8 unusedBuffer[0x1800]; // Unused
     u8 itemIconBuffer[0x800];
     u8 wallpaperBgTilemapBuffer[0x1000];
     u8 displayMenuTilemapBuffer[0x800];