I tried that, but Mario spawned nothing at all for some reason.Man, I can't wait to mod NSMBU! Also, could you make the fire flower shoot hammers? Then it'd be Hammer Suit! Looking forward to kernel exploit!
Also, 'unused' sprites are sprites that were coded into the game by Nintendo, but never used in one of their levels. Some of them crash, others have glitches, most of them work fine. NSMBU has got a surprisingly high amount of unused sprites and settings, there's a lot more to explore than in the previous Mario games