Gain More Points:
Press and release the circle button while in the air.

Access All Practice Levels:
During gameplay hit pause and while holding L1 press the following:
square, up, left, up, circle, triangle
The screen will shake, and you should now go to the "Level Selection" screen where you can access these levels.

Access Cheat Mode:
During gameplay hit pause and while holding L1 press the following:
Circle, Right, Up, Down, Circle, Right, Up, Square, Triangle

Level Select:
During gameplay hit pause and while holding L1 press the following:
Triangle, Right, Up, Square, Triangle, Left, Up, Square, Triangle

Access Specials:
During gameplay hit pause and while holding L1 press the following:
X, Triangle, Circle, Down, Up, Right

Ten More Stat Points:
During gameplay hit pause and while holding L1 press the following:
Square, Triangle, Up, Down

Thirteen More Stat Points:
During gameplay hit pause and while holding L1 press the following:
X, Square(2), Triangle, Up, Down

Big Head Mode:
During gameplay hit pause and while holding L1 press the following:
left, up, x, down, up, x
The screen will shake and you should start a new game to see the Big Heads