MARIO
His skills are the most balanced of the characters.
POWER: (4/5)
SPEED: (4/5)
JUMP: (4/5)
Mario, as always, is an all-around character. He is surprisingly not the best jumper, but can still get his height. He pulls up objects quickly and run's pretty fast. He's great for beginners!

LUIGI
He's got loads of jump ability, but he's rather slow.
POWER: (3/5)
SPEED: (3/5)
JUMP: (5/5)
Luigi is the highest jumper. He is, however, very clumsy and hard to control in both the air and on ground. He's better for an expert player.

PEACH
She can float on air for about 1 1/2 seconds when you hold down A.
POWER: (2/5)
SPEED: (2/5)
JUMP: (3/5)
Peach is the weakest and slowest character of them all. However, she has the best jumping ability. She can get decent height, and can also float temporarily. This allows very long jumps. Peach is perfect for beginners.

TOAD
He has the weakest jump but lots of power.
POWER: (5/5)
SPEED: (5/5)
JUMP: (2/5)
Personally, I think Toad is the best character. He is the strongest and fastest, and his jump isn't much less from Mario's. He's still better for experts. You also may refuse to use him because of his annoying new voice. I like it, myself. ^_^"

Those are all four characters. Yes, only four. The "play as Yoshi" rumor is just that, a rumor. There are no secret characters. For more fake codes, and real ones, try the Secrets/Glitches section!