The following are the types of Marios that are found in the game.
One hit in this form and Mario is dead. He has no powers axcept being able to duck under small passages.
Mario is a bit bigger and is able to break bricks above his head. If he gets hit once he returns to small Mario.
In this form he can smash everything in his way. There is a meter, if you raise it high enough you will get 1-ups.
X or Y button shots fireballs at enemies.
Gives Mario the ability to spin dash into enemies. One hit returns you to being super Mario.
Mario is the smallest he can be, but he's also powerful. He can walk on water and enter very small pipes and wall through narrow paths that even small Mario can't.