At the Options screen: Hold Up, R1, R2, L1, L2 until the screen shakes. Now, you can perform one button Fatalities:
HK: Fatality 1
LK: Fatality 2
To get Chameleon:
At the character select screen, pick any male ninja and hold left, triangle, square, R1 and R2 until fighting starts. Your character should explode into Chameleon!
Hold up and press Start on Sonya. The screen should shake and after you pick your fighter, you get to pick your background.
Playas old characters:
Press Select while choosing Kung Lao, Jax, Rayden, and Kano to play as the old versions.
Thanks to Revolution readers Sarin Kuy, Tim Shelton, Evan Merritt and Kevin Mackie!