What are the cheats for mega man x4?

Answer 1

Play as Dark Zero:

At the Player Select screen, put the cursor on Zero, then press and
hold R1, and press Right, Right, Right, Right, Right, Right. Release
R1, press and hold p, then press u. When the game starts, Zero will be
wearing black armor.

Play as Dark Mega Man:

At the Player Select screen, put the cursor on Mega Man X and press p,
p, Left, Left, Left, Left, Left, Left. Simultaneously press and hold
L1 and R2, and press u. When the game starts, you'll play as Dark Mega
Man.