Buffy The Vampire Slayer

Unlimited health:
Press Y, White, Black(2), White, Y Black(3), Y(3) at the extras screen.
The sound of a scream will confirm correct code entry.
Note: Falls are still harmful.

Multi-player arena 1:
Press Y(4), White, Black, Y(4), White, Black at the extras screen.
The sound of a scream will confirm correct code entry.

Multi-player arenas 1 through 2:
Press Black(4), White, Y, Black(2), White, Y, White, Black at the extras screen.
The sound of a scream will confirm correct code entry.

Multi-player arenas 1 through 3:
Press White(4), Black, Y, White(2), Y(2), White, Black at the extras screen.
The sound of a scream will confirm correct code entry.

Multi-player arenas 1 through 4:
Press Y(2), White, Black(2), Y(5), White, Black at the extras screen.
The sound of a scream will confirm correct code entry.
All four multi-player arenas will be unlocked.

Slayer power:
Press Y(3), Black(3), Y, White, Black(2), White, Y at the extras screen.
The sound of a scream will confirm correct code entry.

Play as Dark Buffy in arena mode:
Press Black, White, Y(2), Black(2), White, Black(2), White, Black(2), White, Black(3), White(2) at the extras screen.
The sound of a scream will confirm correct code entry.

Multi-player story mode:
Enable the "Multi-player arenas" code.
Select any arena, then exit out of it.
Load a saved game and begin game play in story mode.
Press Start on controller two when a major character is encountered during game play.
If more than one major character is encountered in a scene, press Start to scroll through those that are controllable.
Controller two can now be used to control that person.
Press Back on controller two to stop controlling them.
Note: You can also control Bosses.