Make a Character a Lefty or a Righty:
Go to the Character Select screen.
Highlight any player, then press and hold L1 and press X.

Mirror Courses:
Go to the Course Selection screen.
Hightlight any of the courses.
Simultaneously press and hold L1 and L2, and press X.

Change the clothes color of a girl you see during main menu:
At the title scree, while the title logo is bouncing, press triangle, square and X simultaneously

Obtain all characters and courses:
At the title screen, while the title logo is bouncing, while pressing L1+L2+R1+R2 simultaneously, press the directional key up, up, down, up, left, right, right, and left twice. Use the controller in slot 2. If successful, you will hear a sound of the shot.

Sound Test:
While playing with 2 or more players press the four "Shape" buttons onthe other controller and you will hear the game's sound, one for each button