To get the special costumes you must do the following:
Start a new game on normal difficulty. Don't pick up anything. When you get to the gate that leads to the police station go down the stairs. Down there will be Brad Vickers the pilot from Resident Evil he's a ZOMBIE Head past him and go up the stairs. Get the herb from the bushes closest to the stairs. Go in the R.P.D. and get the bullets at the desk in the back of the room. Go back to Brad and fill that damn zombie full of bullets. Inspect him and take the special key. When you get to the dark room there are some lockers use the key to unlock one and get the costumes. With Claire you get a cool denim jacket and the Colt S.A.A. gun. With Leon you either can choose a leather jacket with a skull on the back or a tank top and a baseball hat.
Note: The quickest way to kill Brad is to get close then walk backwards. Let him lunge at your feet then stomp him in the head. This saves a lot of bullets and only takes away 1/8th of you health.
1hit Gator Kill
When you fight the gator boss be starts coming towards you and you see a yellow light on the left wall. Inspect the light it will fall and the gator will eat it. While the light is in his mouth shoot it and the gator will explode.
Infinite SubMachine Gun
The game must be on Normal then complete any reversed game without the use of a first aid spray. You must also have a rank of 'A'.
Infinite Gatline Gun
The game must be on Normal then complete any reversed game without saving. You must also have a rank of 'A'.
Get the Rocket Launcher
Complete all 4 scenarios each with a time of 2 hours and 30 minutes or less. The difficulty must be set on Normal and you must have a rank of 'A'.
Play as Hunk
You must beat all four scenarios with a ranking of A.
The Fourth Survivor
Play all four scenarios as Hunk and get a ranking of A.
Play as Mr. Tofu
Beat the game 6 times over and receive a ranking of A each time.
Reserve Power Control
Press Up Down Up Up Down. Or Up Up Down Down Up.
Play as Akuma
When at the computer in the B games and it says "Enter Guest=" enter the h3 "AKUMA"