Abyss
Enter SDSDRLD as a password. You will lose all health after falling.
Challenge Mode Endurance
Enter MRMDRMD as a password. Stamina restore will no longer be available.
Fatal Blow
Enter LRSRDRD as a password. Enemies have one hit kill ability.
Good Team Performance
Switch characters that you are playing about every 30 seconds to 1 minute or something close to that on a level.[It doesn't matter who you are].
Health
Enter DSRDMRM as a password. Your character will always have full health.
Infinite Shuriken
Enter RSRLRSM as a password.
Lose Shuriken
Enter RLMRDSL as a password. You will not be able to use shuriken.
Mighty Turtle
Enter LSDRRDR as a password. Your characters will no longer be hurt by damage.
New Nexus outfit for Donatello
Enter DSLRDRM as a password.
New Nexus outfit for Leonardo
Enter LMRMDRD as a password.
New Nexus outfit for Michelangelo
Enter MLMRDRM as a password.
New Nexus outfit for Raphael
Enter RMSRMDR as a password.
Nightmare
Enter SLSDRDL as a password. All enemies will have their attacks doubled.
Notes
Use the following key when entering the passwords. The codes have no effect in tournament mode.
D: Donatello
L: Leonardo
M: Michaelangelo
R: Raphael
S: Shredder
Pizza Paradise
Enter MRLMRMR as a password. All health items will be replaced by full HP pizzas.
Play as Casey Jones
Win the Open Brawl Tournament. Alternately, Casey Jones is unlocked five days after a saved game file is created; you can change the system date to do this. Casey Jones replaces Raphael.
Play as Karai
Defeat Karai in the Foot Fight Tournament in less than 150 seconds. Alternately, Karai is unlocked thirty five days after a saved game file is created; you can change the system date to do this. Karai replaces Michaelangelo.
Play as Slashuur
Win the Battle Nexus Tournament. Alternately, Slashuur is unlocked forty five days after a saved game file is created; you can change the system date to do this. Slashuur replaces Leonardo.
Play as Splinter
Successfully complete level 11-7. Alternately, Splinter is unlocked ten days after a saved game file is created; you can change the system date to do this. Splinter replaces Donatello.
Playmates unlocked in bonus materials
Enter SRMLDDR as a password.
Poison
Enter DRSLLSR as a password. Your character will slowly lose HP.
Self Recovery
Enter DRMSRLR as a password. Your character will slowly regain HP.
Squeaking
Enter MLDSRDM as a password. Alternate sounds will play when objects are hit.
Super Defense Power
Enter LDRMRLM as a password. Your defense will be doubled.
Super Offense Power
Enter SDLSRLL as a password. Your attacks will be doubled.
Super-Tough
Enter RDSRMRL as a password. All enemies will have their defense doubled.
Teenage Mutant Ninja Turtles arcade game
Got to level 9-1 and get the hidden Antique. Do this by going down one of the alleyways. There will be a pile of crates and a broken down bus. Jump on the crate and onto the bus. From the bus, jump onto the building . There should be two crates here, containing Pizza and the Antique. Then, complete the level and defeat all the Purple Dragons, Foot, and Mobsters. Next, go to the " 2nd Time Around". If you look through the different objects in the "NY" section, you will see the image of an arcade. Select the arcade to see information on it. When you exit out of the information, the message "Classic Arcade Mode Unlocked" will appear, and that option is now on the main menu at the title screen. Note: Do not worry if the screen remains black, or the arcade main screen takes a long time to load; this is normal.
In the arcade game, press X to get more lives instead of quarters. The joystick and certain buttons including the pause feature do not work. The character selection is just like the arcade. Each controller controls a different turtle. You cannot which turtle to assign to a controller. Controller one is Leonardo, controller two is Michaelangelo, controller three is Donatello, and Controller four is Raphael.
Toddling
Enter SSSMRDD as a password. There will be strange sounds when your character walks.
Unlocking all extra characters
Use the following trick to unlock all extra characters at once. Make sure you have a saved game file for the game. Keep the disc lid open when powering on the Gamecube. Set the system date two or more months ahead from the date that you saved the current game. Insert the game disc and start it. At the title screen, go to "Continue Game". When you get to the level selection screen, go to "Home". You will see every playable character unlocked. To confirm to the game that you have unlocked the extra characters, just exit home, start any stage, and complete it. When you have finished, the game will confirm that you have unlocked the extra characters, as well as other cheat codes.