From WikiCheats

Characters

Mario

Mario, the world's most famous plumber.

You'll start the game with Mario. His special ability is to flip into the 3D world. This lets you bypass obstacles and access hidden items. Using this mode depletes Mario's 3D meter, so he can only stay in 3D for about 30 seconds at a time.

Princess Peach

You gain access to Peach in chapter two. She can use her umbrella as a shield to block attacks and to glide for extended jumps.

Bowser

You gain access to Bowser in chapter three. He can breathe fire, a powerful attack that can also burn a clear path through some areas. His jump also does more damage than other characters. Bowser moves slowly and cannot climb ladders.

Luigi

You gain access to Luigi in chapter six. He can jump farther than the other characters and he has a super jump ability.

Pixls

Pixls are helpers that you collect during the game. Tippi is the first Pixl you find, and is always with you. You may have only one other Pixl with you at a time.

• Tippi lets you see hidden things on the screen. To use Tippi, point the Wii Remote at what you want to see. You get her at the beginning of the game.
• Thoreau lets you pick up and throw enemies. You can throw them off ledges, or onto other enemies. This ability can also be used to activate switches by throwing enemies onto them. Found in Chapter 1-2.
• Boomer is a bomb. He can be used against enemies, or to open cracks in walls or floors. Found in Chapter 2-1.
• Slim lets you turn sideways. You can use this to slip into narrow passageways. Because Mario is 2D, this makes him disappear. Found in Chapter 2-3.
• Thudley makes earthquakes. He can be used as a weapon or to get past obstacles. Found in Chapter 3-2.
• Carrie can transport you across gaps. Found in Chapter 3-4.
• Fleep can reverse things. This reveals or activates doors, portals, or items. Found in Chapter 4-2.
• Cudge is a hammer, and an excellent weapon. Found in Chapter 5-2.
• Dottie shrinks your character. This allows you to enter small doors, and enter special small stores. Found in Chapter 5-4.
• Barry is a shield. Found in Chapter 3-1.
• Piccolo is a music player. She can send enemies to sleep. Found in Chapter 7-3.
• Dashell increases your run speed. Found at the bottom of the Flipside's Pit of 100 Trials.
• Triton remplaces Tippi, when she leave the game with Bleck. Found in Chapter 4-4, for 1000 coins.