Hmm... I don't know for sure, but I think Mario could only shoot Extended Sprites, 'cause the Mario fireball is an extended sprite and, well, you know the rest...
With some clever tweaking in pure hex, it might be possible to change the right offset in the Rom so the fireball-shooting routine points to Normal sprites instead of Extended sprites... However, you'd also need to change several other pointers, specifically the ones for X and Y position and speed for the fireball, since the game uses different Ram Offsets for normal sprites and Extended sprites.
Sorry to shoot you down like that, kid... If you knew how to use MiOr's Extended SpriteTool, though, you could change the Mario fireball into something else... like a hammer from SMB3, or an exploding grenade, or other things... Hehe... (Extended SpriteTool uses different ASM patterns than Normal SpriteTool and I have no idea how to code with it. I wish I did, though.)
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