Start a new game on any difficulty and play up to the point where Bruce Wayne gets his Batsuit. Save then exit game. Reboot game disk then select your save slot. Before continuing story quickly enter this code on the d-pad
Left, Left, Down, Down, Left, Left, Right, Up, Up, Down
You'll hear a sound if done correctly. Now select continue and pick your Batsuit and enjoy. You will have to put in this code every time you reload your game.