In case you have to fight Zero, use the following tricks. There are only four weapons that will harm Zero: the Third Charged Shot, the Final Charged Shot (Enhanced Cannon required), the Speed Burner, and the Dragon Punch. Zero will block any other weapon. Note: The Dragon Punch will strip half of his health away. When Zero dashes at you, climb up the closest wall you are near -- after he stops dashing, he will pound the ground, causing four rocks to shoot up. You can jump over them. Zero has two projectiles. One is a small green shot which he will fire if you are shooting at him. The second is his trademark Z-slash combo, where he will fire two Third Charge Shots and end with a Beam Saber Slash. The shots will not hurt much, but his Beam Saber will cause drastic damage. Be careful and you will defeat Zero with ease.