Infinite stamina:
At the main menu, press R1, R1, Triangle, R1, R1, Triangle.

Big women wrestlers:
At the main menu, press R1, R1, Triangle, Triangle, L1, L1.

Indestructible weapons:
At the main menu, press L1, R1, L1, R1, Square, Square.

Low gravity:
At the main menu, press R1, L1, L1, L1, Square, Triangle.

Rude grunts:
At the main menu, press R1, L1, R1, L1, Triangle, Triangle.

Tiny wrestlers:
At the main menu, press R1, R1, L1, L1, Square, Square.

Medusa:
Get a fight going in the ladies bathroom in Hardcore Challenge mode to unlock Medusa. 

Kronik:
Set your opponent on fire in the block in Hardcore Challenge mode to unlock Brian Adams and Bryan Clark. 

La Parka:
Knockout your opponent with the steel chair in the truck area in Hardcore Challenge mode to unlock La Parka. 

Vampiro:
Set your opponent on fire in the truck area in Hardcore Challenge mode to unlock Vampiro. 

Mike Awesome:
Throw your opponent through a table, bench, or couch in the secret area of the block in Hardcore Challenge mode to unlock Mike Awesome. 

3 Count:
Hit your opponent over the head with the TV in the media center in Hardcore Challenge mode to unlock the three members of the 3 Count. 

Vince Russo:
Knockout your opponent with the briefcase in the media center or parking lot in Hardcore Challenge mode to unlock Vince Russo. 

Lance Storm, Mike Awesome, Lt. Loco, Doug Dillinger:
Successfully complete Hardcore Challenge mode on the easy difficulty setting with any male wrestler to unlock Lance Storm, Mike Awesome, Lt. Loco, and Doug Dillinger.