Unlock ALL Levels:
Press B, Y, X, B, L, X, R, L, X, R, B at the Main menu

Unlock ALL Characters and Levels:
Press Y, B, X, Y, Down, Right, Up, Left, L, L, Right, Right, Down, Up, R, X, Left, B, B, Down at the Main menu.

Complete ALL Current Objectives:
In Story mode pause gameplay and press X, X, B, X, X, Y, X, X, L, R. If you have entered the code correctly a screen will appear telling you that you have completed ALL objectives. Entering the code does not effect scooter icons and players.