If you're talking about his final stage, get used to dodging to the side. A lot of people make the mistake of just dodging backwards as a reflex but you want to train yourself not to do that because all of his attacks move mostly straight forward when he's not jumping around. So if you dodge back you just put yourself in line to get hit more. You want to get comfortable and get used to trying to stay up his arse. It's a handy tool to have in your belt for most boss fights. Staying calm, and staying close