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

Holiday Outfits
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

Unlock Challenge Mode
To unlock Challenge Mode, defeat Story Mode with all four turtles

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.

Password List
Enter these codes in the Password screen of the Options menu

DMDML Raphael Alternate Costume
LDMSR Leonardo Alternate Costume
RRLMD Michaelangelo Alternate Costume
DDSMS Donatello Alternate Costume
RDSRL Raphael Attack Power Up
LMLSD Leonardo Attack Power Up
SMRDL Michaelangelo Attack Power Up
DRLDS Donatello Attack Power Up
LRMDS Raphael Defense Doubles
MRLLM Leonardo Defense Doubles
MRRML Michaelangelo Defense Doubles
SSSMR Donatello Defense Doubles
SLDSM Raphael Double Power Up
LSLSR Leonardo Double Power Up
MMSLR Michaelangelo Double Power Up
DMDRS Donatello Double Power Up
DRDSS Michaelangelo Unlimited Fire Shurikens
SMRDM Leonardo Unlimited Shurikens
LSDRM Unlock Playmates Toy Data Base
MSRLS Unlock Splinter (Story Mode)
SMMRS New Sound Effects