While SMB3 certainly had a lot of stuff, and also bearing in mind that I'm not a fan of the 3D games, and I may be mistaken, I think that's false.
SMB3 Powerups:
Mushroom
Flower
Leaf
Tanuki Suit
Frog Suit
Hammer Suit
Star
P-Wing
The additional special items:
Jujem Cloud
Kuribou Shoe
Hammer
Recorder
Misc
1-Up
THat's thirteen. (I don't recall any that I had missed.)
Galaxy 2 had 12 special powerups, alone, plus the normal stuff.
THen, there's Super mario RPG, if you count that.
I can't follow all of the powerups in the 'New SMB' and the 3D World series. Lots there, too, but Galaxy 2 takes the biscuit.
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SMB3 Anecdote
I had always played the JP version of the game, and in that version, being hit while powered up with a leaf or flower, reverts you to small Mario. The non-JP version is severly Nerf'd.
(Emphasis, mine).
Do you have any references on this? I find it quite fascinating, and I wonder what form it would have taken. Heck, I'd have played it. I happen to enjoy the SMB film.
I feel like making this, now, and giving the code to Nintendo; or selling it as WiiWare. People would play...and /buy/ this for the camp factor.