Metal Mario
Play as Wario in Normal Mode in story and after you defeat Rudy you will get Metal Mario, but you can't lose, and redo is the same as losing.

Virus Multiply
In marathon mode, you can multiply the amount of viruses by pressing L or R.

Vampire Wario
Finish story mode on ant difficulty and defeat Vampire Wario to unlock him in vs mode but you can't lose, and redo is the same as losing.

Get Level 21
Beat level 20 in classic mode to unlock the all new level 21 with 88 viruses.

Harder Gameplay
After finishing the game in story mode without continuing, you will unlock superhard mode! to access it, highlight the "hard" option at the difficulty-select screen in story mode and press the z button; the "hard" button will change to "s-hard."

Skill Level Control
In the Vs.computer mode,hold the L button when selecting the opponent to adjust their skill level

New Virus Levels
To get virus level 21 just beat virus level 20 in classic mode.Now to get level 22 you must beat virus level 21, when you finish the game credits will appear, but DON'T TURN OFF THE GAME.When the credits are done scrolling virus level 22 appears with 92viruses, but there are no redo's. If you lose you have to beat

Change AI Settings In VS. Mode
At the Character Select Screen, highlight a character. Hold L and Press A to increase AI of that character. Hold L and Press B to decrease the AI of that character.