Unlock Level Select:
Press Up + Start with Sonya highlighted and you will be able to select 1-Player or Vs mode.

Select Battle Arena:
At the 'Character Select' screen press Up + Start with Sonya highlighted and you will be able to select your fighter and pick your Battle arena.

Unlock Unlimited Credits:
When you are at the Story screen press Down, Down, Up, Up, Right, Right, Left, Left.

Unlock Chameleon Kode:
Select any male Ninja and on the D-pad hold back and press R1, R2, Triangle, square until the character changes color.

Unlock Old Characters:
When you have either Rayden, Jax, Kung Lao or Kano highligted press Select.