At the 'Main' menu hold LB and enter the code and then release LB. If you have entered it correctly you will hear a confirmation sound.

Unlock Donatello's Big Head:
Enter B, Y, A, X.

Unlock Challenge Map 2:
Enter A, A, B, A.

Complete the following tasks to get the corresponding GamerScore.

Get Your First Coin - GamerScore 15:
Get your first coin.

Family Unit - GamerScore 15:
Do a Co-Op move combination attack.

Mystical Jungle - GamerScore 20:
Complete Level 1.

Vigilantism - GamerScore 24:
Complete Level 2.

Techno Ninjutsu - GamerScore 28:
Complete Level 3.

Used Dons Special Move - GamerScore 30:
Used Don's special move.

Used Leo's Special Move - GamerScore 30:
Used Leo's special move.

Used Mike's Special Move - GamerScore 30:
Used Mike's special move.

Used Raph's Special Move - GamerScore 30:
Used Raph's special move.

Cowabunga Carl Getaway - GamerScore 32:
Complete Level 4.

Spirit of the Forest - GamerScore 36:
Complete Level 5.

Ninja Tag Time - GamerScore 40:
Complete Level 6.

The Game is the Foot - GamerScore 44:
Complete Level 7.

Foot Trail - GamerScore 48:
Complete Level 8.

Clean Sweep - GamerScore 50:
Without taking any damage complete a level.

Tower Power - GamerScore 52:
Complete Level 9.

When the Slime Comes - GamerScore 56:
Complete Level 10.

O Brother Where Art Thou - GamerScore 60:
Complete Level 11.

Bite Me! - GamerScore 64:
Complete Level 12.

All is Forgiven - GamerScore 68:
Complete Level 13.

Ninjas in the Crypt - GamerScore 72:
Complete Level 14.

The Mysterious Leader - GamerScore 76:
Complete Level 15.

Winter's Secret - GamerScore 80:
Complete Level 16.

Complete following tasks to unlock the corresponding GamerScore.

In the Dark - GamerScore 0:
Fall into a manhole 5 times.

Ninjitsu - GamerScore 10:
Defeat 3 opponents with a direct attack.

Lickity Split - GamerScore 10:
In less than 2:00 minutes clear out the Apartment and April’s Loft.

Lofty Goal - GamerScore 10:
In a Local game clear out April's Loft losing 10 health or less.

Deep Freeze - GamerScore 15:
Without getting frozen get past the freezing trap in the Technodrome.

Superhero - GamerScore 15:
Destroy ALL Parking Meters, Barrels, Pylons and Speed Signs in the game.

Evade - GamerScore 15:
Losing 20 or less health defeat General Traag in the Technodrome.

Fire Hazard - GamerScore 20:
Without getting burned by the flamethrower rescue Master Splinter.

Slice and Dice - GamerScore 25:
In an Xbox Live Co-Op game get 250 individual points.

Turtle Soup - GamerScore 25:
Without getting turned into a regular turtle defeat Shredder.

Real Ultimate Power - GamerScore 30:
In an Xbox Live Co-Op game defeat Shredder.