Mortal Kombat 2

In the black and white copyright screen, type : AICULEDSSUL

You should hear a chime.
Then on the next few screens, you can hit F9 to bring up the cheat screen.

SECRET CHARACTERS:
~~~~~~~~~~~~~~~~~~
Both Jade and Smoke can be seen in the Living Forest when they look out 
from behind the middle trees.  They occasionally drop down during a 
match and give clues on how to reach them.  After you win or lose to any 
of the secret characters, you are returned to the Choose Your Fighter 
screen where you may pick another character.

Smoke clues:                       Jade clues:

I Am Called Smoke                  I Am Called Jade
Toasty                             Before The ?
You Can Start Finding Me           Ermac Who?
Ermac Who?                         I Will Meet You In Goro's Lair
You Can Not Defeat Me              Chun Who?
I Am One Of Three                  I Am One Of Three
Portal                             Restrict Yourself
I Will Meet You In Goro's Lair     Alone Is How You Will Find Me
Mortal Kombat One                  One Day We Will Fight!
Prove Yourself                     Bring On Kano And Sonya!

TO REACH JADE:
~~~~~~~~~~~~~~
Win one round on the stage directly before the question mark 
using only LOW KICK.  That is the only requirement.  You may not press 
BLOCK.  You may reach Jade on any round of the stage.  Unnecessary 
requirements include flawless victories, fatalities, and a certain 
number of wins.


TO REACH SMOKE:
~~~~~~~~~~~~~~~
Be on The Portal stage.  You may be playing either a one or 
two player match.

Wait until the face pops out in the lower right corner and 
says "Toasty!".  The face will appear when you uppercut your opponent, 
or your opponent uppercuts you.  There is no determined way to get the 
face to appear more frequently.  It can appear a few times during a 
match or not at all.

As soon as the face appears, press the start button while 
holding down on the joystick.  In a one player game, make sure the start 
button pressed is on the side you are playing on.  In a two player game, 
whoever presses their start button first will be the one who will fight 
Smoke.

TO REACH NOOB SAIBOT
~~~~~~~~~~~~~~~~~~~~

Win 50 games in a row.  You must fight against another player 
for at least part of the time.

If you lose to Noob Saibot, you may fight him again by winning just one 
more game or round.  Apparently the computer only has 49 wins tracked if 
you lose to Saibot, so you can theoreticly fight him over and over, as 
long as you lose to him.  And in case you did not notice, Noob Saibot is 
actually Boon Tobias backwards.

PONG:
~~~~~

You have reached the outer limits of the tournament.  Now you both must 
face a challenge from your past...  Pong!  First player to seven wins.  
Pong occurs after 250 matches.  This might have been reduced in version 
3.1.

THINGS TO TRY:
~~~~~~~~~~~~~~

Right after doing the pit fatality uppercut, hold down on 
both joysticks.  The body will slowly slip from the spikes and fall to 
the ground.

During attract mode, pull down on either joystick to bring up 
the top 15 players.

Do Reptile's tongue fatality on The Armory stage and watch 
the floor.  This is most likely a glitch and does not involve a secret 
room or character.

Random select may be done by pressing up and start from the 
Choose Your FIghter screen.  Be sure to have the selector positioned 
where it appears originally.

To turn throws off in a two player match, hold down and HIGH 
PUNCH on both joysticks after you select your fighters.  A message will 
appear saying throws are disabled.  Other "power-ups" may be possible.