Change your system's date to either December 24th or 25th to see the turtles in Santa garb. Change it to October 31st to wear a pumpkin on your head.
Hun
Successfully complete level 6 as Michaelangelo to unlock Hun in versus mode.
Improved Weapon For Michaelangelo
Enter MSRMM as a password, and Michaelangelo will get an improved weapon in Story Mode.
Oroku Saki
Defeat Saki as Raphael, Donatello, Michaelangelo, or Leonardo to unlock Oroku Saki in versus mode.
Password List
Enter these codes into the Password screen in the Options menu:
Alternate Costume (Raphael): SLSMM
Alternate Costume (Leonardo): RSLMD
Alternate Costume (Michaelangelo): RLSLS
Alternate Costume (Donatello): RRSLR
Attack Power Up (Raphael): RDSRL
Attack Power Up (Leonardo): LMLSD
Attack Power Up (Donatello): DRLDS
Defense Doubles (Leonardo): LDSMS
Defense Doubles (Donatello): MLMLS
Defense Doubles (Michaelangelo): MRRML
Defense Doubles (Raphael): SDRML
Defense Power Up (Michaelangelo): MSRMM
Change Sound Effects: DDDML
Power Up Effects Double (Raphael): LSMMS/RSSSR
Power Up Effects Double (Donatello): MLSDS
Power Up Effects Double (Michaelangelo): RLMSM
Power Up Effects Double (Leonardo): RSDMM
Unlimited Fire Shurikens/All Food is Pizza (Michaelangelo): MSSLD
Unlimited Shurikens (Leonardo): SSLDM
Unlock Playmates Toy Data Base: LSDRM
Unlock Splinter for Story Mode: LSLML
Playmates Database
Enter LSDRM as a password to unlock the Playmates Database.
Shredder
Defeat Shredder as Raphael, Donatello, Michaelangelo, or Leonardo to unlock Shredder in versus mode.
Splinter
Successfully complete Dojo level 3 as Leonardo to unlock Splinter in versus mode.
Team Attack
In 2-player mode, press X and SQUARE at the same time to get into a stance. Then have your teammate come next to you, face you, and then press X and SQUARE at the same time. You will perform a special team attack where you are thrown into enemies, hurting them.
Unleash the Secret of Gembu
Beat the third Dojo Stage with all four turtles to learn the Secret of Gembu maneuever. Use the move to damage everyone on the screen. You'll have three opportunities per level to use it.
Unlock Casey Jones
Go to options, then go to password and type in SRLMD. In story mode pick him and when you start an area press Y, he'll say ''Casey Jones is on the job.''
Unlock Challenge Mode
To unlock Challenge Mode, defeat Story Mode with all four turtles.
Unlock Characters For Vs. Mode
Fulfill the following criteria to unlock the corresponding characters for Vs. Mode:
Casey Jones: Beat Stage 1 with Raphael
Evil Turtlebot: Beat Stage 3 with any turtle
Hun: Beat Stage 6 with Michaelangelo
Splinter: Beat Dojo Stage 3 with Leonardo
Shredder: Beat Shredder with any turtle
Oroku Saki: Beat Saki with any turtle
Yoshi Hamato: Beat Challenge Mode with any turtle
Unlock Levels for Story Mode Stage Select
Complete a level to unlock it in Stage Select.
Yoshi Hamato
Successfully complete Challenge Mode as Raphael, Donatello, Michaelangelo, or Leonardo to unlock Yoshi Hamato in versus mode.