(last update - Aug 19 2010)
Total current cheats: 12
print meBattle Oroku Saki (Shredder's true form)
(Okay, this isn't a cheat anyway) Just complete Story Mode with all four of the turtles (do it in any order) and with the fourth one, Shredder flees into his Shinto Palace rather than falling from the heliport. The battle has no power ups, but at the start of the battle, you'll get all 6 of your lives back (cool)! The battle will be easier with a supply of electric and/or fire shuriken. Use your supplies first. Ordinary shuriken and weak attacks are useless against him. Also use Gembu (complete Special Stage: Ordeal with all four turtles. Control with L1). Even when he turns red but after one Gembu, run away until the recovery time is over, so you can use it again. This strategy should defeat him before you can say "Cowabunga!" Enjoy the extra clip.
print meMore tips
Tip #5: Attacking Tip
Okay, if a character is powerful, it is not everything. Look at the defense. Splinter has much more attack than the turtles, but Saki is twice as hard with Splinter's low defense.
Tip #6: Finding Makimonos
If you want to find more makimono scrolls, go into places you would not normally go, and attack in the middle of nowhere to find hidden crates. Like, for instance, if you are Leo is Sewer, go backwards at the beginning to find a scroll hidden in a wall.
print meOkay, a few tips
Hello, I am very good at this game, and I have a few tips for you if you want to be a very good player on this game.
Use Small Attacks Often
This may sound crazy, but the game is much harder if you're going around hitting enemies with  attacks. They may be stronger, but small attacks don't knock the enemy down, and saves time. The game is very difficult because they are much slower, too. Also, hit X multiple times to do combination attacks.
Oroku Saki Tip
Whenever you fight Saki in the end, either use Don or Mike. Leo and Raph are good, but Raph's going to get the crap beaten out of him with his low range, and Leo is not agressive enough. Don has far reach and can knock Saki down, and Mike's quick attacks can be a weakness for Saki.
Nano Monster 3.0
After oil drums are gone, the Nano Monster is still vulernable to attacks. Mike's incredible jump attack is very useful to use on the huge robot's head. I got 20 combos on his head with this advantage.
Challenge Mode Tips
.Use Mike for challenge mode, especially for Dr. Stockman. His jump attack can damage Stockman. The other bosses are easier, too.
.Also, collect as much shuriken as you can cause some bosses are nearly impossible without shuriken, without dying; Hun, Shredder, Saki, and Yoshi. Fire shuriken work the best.
print meTo get better times
Don't go for boxes that you don't need. If you have almost full health, don't run off to a hidden area to look for a pizza just for the good of it, just keep going.
print meChristmas Easter Egg
Set your system clock to December 25th (Christmas). You'll see your turtle wearing a Santa Hat.
print meHalloween Easter Egg
Set your system clock to October 31st (Halloween). You will see your turtle with a pumpkin for a head.
print me4 More Cheats!
Put these cheats in the password place.
New costume for Michelangelo: RRLMD
Michelangelo Gets Unlimited Fire Shurikens: DRDSS
Michelangelo has double defense: RLDDR
Improved Weapon for Michelangelo: MSRMM
print meAll pizzas
To make all recovery items pizzas, (for Michelangelo,) type in DRDSS at the codes section.
print meCheats for Alternative Costumes
Alternate Donatello costume:
Enter Splinter, Raphael, Splinter, Michaelangelo, Michaelangelo as a password. Then hold L1 or R1 when selecting Donatello at the character selection screen.
Alternate Leonardo costume:
Enter Raphael, Michaelangelo, Michaelangelo, Leonardo, Leonardo as a password. Then hold L1 or R1 when selecting Leonardo at the character selection screen.
Alternate Michaelangelo costume:
Enter Raphael, Raphael, Leonardo, Michaelangelo, Donatello as a password. Then hold L1 or R1 when selecting Michaelangelo at the character selection screen.
Alternate Raphael costume:
Enter Leonardo, Michaelangelo, Splinter, Donatello, Donatello as a password. Then hold L1 or R1 when selecting Raphael at the character selection screen.
print mePassword Cheats
Enter these codes at the Password Screen on the Opeinos menu
Goofy Sound Effects- SMMRS
Unlock playmates toys- LSDRM
Unlock splinter story mode- MSRLS
Alternate Costume- DDSMS
PowerUp 1- DRLDS
PowerUp 2- SSSMR
PowerUp 3- DMDRS
Alternate Costume- LDMSR
PowerUp 1- LMLSD
PowerUP 2- MRLLM
PowerUp 3- LSLSR
Unlimited Shuriken- SMRDM
Alternate Costume- RRLMD
Unlimited Fire Shuriken- DRDSS
Alternate Costume- DMDML
PowerUp 1- RDSRL
PowerUP 2- LRMDS
PowerUP 3- SLDSM
PowerUP 4- MSLLR
print meSound Effect
At title screen, enter this to get sound effect to your turtle's footsteps
Squeaky Feet- Up,Up,Down,Down,Left,Right,Left,Right,X,Circle
print meUnlimited Health
Put in SMDRL at the password option. Then play the game and you will never get hurt.