Quake 3 - Revolution cheats and cheat codes for Playstation 2

Skip Level:
During a game play, hold L1 + R1 + R2 + Select and press X, Circle, 
Square, Triangle, X, Circle, Square, Triangle.  

Unlock two bonus characters and level
Finish campaign mode on the "I Can Win" difficulty mode.

Pause in multi-player mode
There is no pause option in multi-player mode.
But you can stop the game play with the following trick:
Press Start, then highlight "Quit" and push X. 
It will not quit unless you select "Yes". 
To continue the game, select "No".