There are two ways to fight Cut Man in this game.

1. If you have a Command Mission (PS2 game) save file on your memory card, you can fight Cut Man after defeating Optic Sunflower.

2. At the title screen (when it says "Press Start"), press left, circle, up, triangle, down, X, right, square, L1, R1, L2, and R2. Start a new game, and you'll be able to fight Cut Man after defeating Optic Sunflower.