Mortal Kombat 4 Cheat Codes for Arcade

Make the Computer Perform a Fatality
When you lose the fatality round to your opponent, hold HK + HP. When you hear "FINISH HIM!" the CPU will perform His/Her fatality.

Play as Meat
To play as Meat, beat the game on Team Mode then play again and you'll be playing a Meat. Meat will have the moves of the character you selected.

Alternate Colors
To change your fighters color or clothing, press the following button sequences at the character select screen:

Kai: Hold Start, HP+BL+LK
Raiden: Hold Start, LP+BL+HK
Shinnok: Hold Start, HP+BL+LP
Liu Kang: Hold Start, HK+BL+LK
Reptile: Hold Start, LP+BL+LK
Scorpion: Hold Start, HP+HK+BL
Jax: Hold Start, RN+LP+BL
Reiko: Hold Start, RN+HP+LK
Johnny Cage: Hold Start, RN+LP+LK
Jarek: Hold Start, HK+HP+RN
Tanya: Hold Start, HK+LK+HP
Fujin: Hold Start, LP+HP+HK
Sub-Zero: Hold Start, RN+BL+HP
Quan Chi: Hold Start, HP+RN+HK
Sonya: Hold Start, LK+HP+RN

Automatic Combos
At the Character Select screen, hold START on the character you want to be and press LK HK RN.