Master code
Press L, R, L, R, X(2), Y(2) at the main menu. A sound will confirm correct code entry.

Unlimited electric Batarangs
Press L, R, B, White, L at the main menu. A sound will confirm correct code entry.

Bonus characters
Press Left, Right, Down, White, L + R, then press Start at the main menu.

Unlimited Batarangs
Press L, R, White, Y at the main menu. A sound will confirm correct code entry.

SWAT Chase: Envelope D
You will enter the elevator shaft. Ride the elevator all the way down until it stops. Get off the elevator and wait for it to rise again. After it rises, jump down to the bottom and use first person mode to find the control box. Use a Batarang to disable it and the door behind it will open. Stay clear of the elevator and wait for the correct time to get in the open room. Inside the room is "Secret Key 2." Get out of the room and ride the elevator up to the top. At the top there is a door that is supposed to be locked. The key opens the door, and inside is an envelope with the letter "D" on it. Finish the game and the "Infinite Special Move Bar" cheat will be unlocked.

Bonus characters
Press Left, Right, Down, White, L + R, then press Start at the main menu.

Rooftop Battle: Envelope A
When the clowns chase Mary, you will go up to the rooftops. Grapple hook up to her roof and beat up the white clown. Go up to the next roof, where you are on a little balcony. Jump across, then go in to see a thug run across a hall with the girl. Follow and he will jump off the roof. Follow, look down, and drop to lowest edge. Walk along to left until at the corner the grapple icon appears Grapple over, go in the door and pick up Envelope A.