Mortal Kombat 2 - 30 kredits

Fight Against Smoke:
At the character select screen hit Up, Left, Up, Up, RightSelect.

Fight against Jade:
Up, Down, Down, Left, RightSelect.

Fight Kintaro:
Up, Down, Down, Right, RightSelect.

Fight Shao Kahn:
Right, Up, Up, Right, LeftSelect.

Fight Noob Saibot:
Left, Up, Down, Down, RightSelect.

Pong mini game:
Win 250 vs. mode matches.

Fight as Smoke:
Win 50 two player matches.

Baraka Fatality:
Get close and hit Foward, Foward, Down, X.

Jax Fatality:
Block, Block, Block, Block, B.

Johnny Cage Fatality:
Get close and hit Foward, Foward, Down, Up.

Liu Kang Fatality:
Foward, Foward, Back, Down, X.

Reptile Fatality:
Get close, Forward, Forward, Down, X.

Scorpion Fatality:
Block, Up, Up, Y.