These are the moves for
Mortal Kombat 2. Only some of the special moves, and none of the finishing moves, are applicable to other MK games.
Special moves
Acid Spit: Forward, Forward, High Punch
Force Ball*: Back, Back, High Punch + Low Punch
Slide: Back + Low Punch + Low Kick + Block (+ = simultaneously) (Works well just after you've knocked your opponent on the ground)
Invisibility: Hold Block, Up, Up, Down, release Block, High Punch
Finishing Moves
Invisible Upper Body Removal: Standing next to the opponent, turn on invisibility, then press Forward, Forward, Down, High Kick
Head Chomp: From about half a screen away, press Back, Back, Down, Low Punch
Babality**: Down, Back, Back, Low Kick
Friendship** (Shameless self-promotion) : Back, Back, Down, Low Kick
Kombat Tomb/Pit II : Down, Forward, Forward, Block
* While executing this move, the fact that you're crouching prevents you from being hit by certain projectiles
** Of course, you cannot do a babality or friendship if you've done any punching in the winning round