I don't really understand what I am supposed to do but I don't think what I was doing was the meant way to play. So I spent the entire game with my zip head off the main body and kept on attacking the boss and I practically didn't take any damage during any of the three bosses. Idk if that was luck or if that was the idea.
Anyways, to me the bosses felt pretty easy to defeat, and not much of a challenge, chomper feels way worse than roller, I didn't even switch to chomper during that run. But the game has some astonishing visuals, cool asf main menu, and I love the music.