Mortal Kombat 2 - Kodes

Dead Pool - When you or your opponent knocked into the Dead Pool, press Down on the joystick to hear Dan Forden say "Hello" in a British accent.
Disable Throws - When V.S screen comes up, press and hold Down + HP on both joysticks.
Random Select - At select screen, press Up + Start to have the CPU select a fighter for you.

SEGA GENESIS
Secret Menu: In the options screen, put the cursor on "Done" and then press Left, Down, Left, Right, Down, Right, Left, Left, Right, Right. The new option should appear. 
Fergality: This special a Fatality must be performed using Rayden and in the background with the big dragon in the wall. In the special option screen, set it to "Ooh, Nasty!" When the you are instructed to "Finish Him/Her!" press the following buttons: B - B - B - START
Kombat Tomb: When you or your opponent are uppercut to the spiked ceiling, pull down on both joysticks to make the character to slide off the spikes.

SUPER NINTENDO
Team Battle Mode: At the Start/Option screen, press and hold L+R, and press START. When you select your fighters, you could do the Random Select instead. Hold UP and hit START.
Destroy the Logo: When you turn on the SNES, immediately hold L and R to watch Shao Kahn and Kintaro destroy the logo.
Kombat Tomb: When you or your opponent are uppercut to the spiked ceiling, pull down on both joysticks to make the character to slide off the spikes.
The kodes listed below, must be done in the character select screen.
One Hit Kill: D, U, R, U, L, Select
Extra Fatality Time: U, U, L, U, D, Select
Fight Shao Kahn: R, U, U, R, L, Select
Fight Kintaro: U, D, D, R, R, Select
Fight Smoke: U, L, U, U, R, Select
Fight Jade: U, D, D, L, R, Select
Fight Noob Saibot: L, U, D, D, R, Select

SEGA SATURN
Switches Menu: As soon as the opening cinematics start, enter D, U, L, L, A, R, D, B, Y, C. Now go to the Main Menu, and you will see a new option named "Switches." You can turn on 1-hit wins, continuous Toasty!, and more.

32X
Test Modes Menu: From the title screen, go to Options. At the Options screen, highlight "Done." Now press L, D, R, R, D, L, L, L, L, R, R, R. Now a new option called "Test Modes" should appear.

HIDDEN CHARACTERS
Jade (Saturn, Genesis & SNES): At the stage before the "?", use nothing but LK and win one round.
Smoke (Saturn, Genesis & SNES): Press Down + Start at the Portal stage when Dan Forden says "TOASTY!"
Noob Saibot (Genesis): Win 25 matches.
Noob Saibot (Saturn, SNES & Arcade): Win 50 matches.