It really doesn’t matter whether you go pick up rings or not. Even the bullets that aren’t homing still do stuff, so press B even if your not locked on. All you really have to do is keep a mass of bullets continually aimed at him. Essentially you can hit him at any time if you can make it (You’ll know when you’ve hit him because he will flash red and the health meter in the top corner will start to decrease). You can’t do this when your not standing on a box because your too low… At other times he will land and will begin shooting missiles at you. During this time you can jump onto the surrounding boxes, jump up when he comes to you and hit him. Next wait for your enemy to fly around shooting his machine gun. First grab some rings, they’re spread throughout the arena. All you have to do is hit him on the top side.