Question mark menu:
Hold Up + Block + Run at the options screen until it shakes.

Classic characters:
Highlight Jax, Kano, Kung Lao or Raiden, then press 7 or X.

Stage select:
Highlight Sonya Blade at the character selection screen. Hold [Up] +
[Enter] or [Up] + Z. The screen will shake to confirm correct code entry.

Fight as Chameleon:
Choose any male ninja (Reptile, Classic Sub-Zero, Rain, Human Smoke,
Ermac, Noob Saibot, or Scorpion) and hold [BACK] + [LP] + [HP] until
the fight starts. Chameleon is a semi-clear ninja that morphs into all the
other ninjas in the game. When the fight begins, your ninja will explode and
change into Chameleon.

Debug coordinates:
Press N during game play.