Play As Meat
Choose group mode and play against all 15 characters in 2 player mode. After finishinishing with the last character which is Sonya, your next character will be Meat. Meat has the previous character's moves.

Play as Goro or Noob Saibot
For either of these to work, you must first beat the game with Shinnok & Reiko.

Goro: At the select screen, select the "hidden" option with the run button, and keep holding run. Move up to Shinnok and, while still holding run, select Shinnok with the Block button. Keep holding BL and RN until the round starts, and you are Goro!

Noob Saibot: Start a two player game. Do the Noob Code (012-012). Win with either player, make sure to continue. Now, repeat what you did with Goro. Select hidden with the Run button, hold it, go up to Reiko, then press and hold Block along with Run.

Codes
100 100 = Throwing Disabled
111 111 = Free Weapons
444 444 = Start with weapons drawn
333 333 = Randper Kombat
222 222 = Start with Random Weapon
555 555 = Many Weapons
666 666 = Silent Kombat
050 050 = Explosive Kombat
020 020 = Red Rain (Only in the Rainy Stage)
002 002 = Can't loose Weapons
123 123 = First Hit Wins
002 002 = Permanent Weapons
012 012 = Noob Saibot Mode
110 110 = Disable Throws and Maximum Damage
010 010 = Disable Maximum Damage
001 001 = Unlimited Run
060 060 = No Rain (Only In Rainy Stage)
321 321 = Big Heads

Play At:
303 303 = The Prison Stage
101 101 = Shaolin Temple Stage
011 011 = Goro's Lair
022 022 = The Well (Scorpion's Stage)
033 033 = Elder Gods (Blue Face)
044 044 = The Tomb Stage
055 055 = The Rain Stage
066 066 = Snake Stage
202 202 = Living Forest
313 313 = Ice Pit