Here are some cheats and tips for the game Mortal Kombat Trilogy.
Play as Chameleon
At the fighter-select screen, select any male ninja. At the loading
screen before the match, simultaneously press and hold Left, Block,
Run, High Punch, and High Kick until the fight starts. If you did the
trick correctly, just before the fight starts, your character will
explode into the hidden fighter Chameleon.