On the main menu screen, choose ''New Game'' and start a two-player game. In the middle of play, take controller 1 and press and hold R + X + Y + B. With these held, press A. This will allow you to damage your partner. To turn this mode off, just do the trick again.
8/16/2001
Radar Map
Pause the game and press Up, Down, Up, L, R, L. If you entered the code correctly Yoda will laugh and you'll have a radar map that shows the location of enemies and hostages.
8/16/2001
Return to Last Checkpoint
After losing all lives on a level, continue the game and enter the same level. Pause the game and enter L, R, L, L, R, R, L, R, R, L. If you entered the code correctly, you'll go to the last checkpoint you passed before dying.