i never got hit once in that fight that you are talking about with the water platforms
infact he is the easiest out of all of the bad guys
He kept teleporting above me, so I'd have to hop into the water and swim to another platform. Link was too slow to get there in time so I'd end up getting hit by the trident or an ice block while completely defenseless, which took me down to 1 quarter of a heart. I also couldn't get two consecutive arrows on him for a stun either. I'd shoot once, he'd get angry, I'd dodge an attack, put an arrow on my bow and then he'd teleport (usually above me).
all you have to do is shoot his eye with a shock arrow and he falls down
I would get one shot off and then he would teleport, which made it so I was only ever able to stun him about three times during the whole fight. Ended up wasting all the shock arrows, all my fire arrows, and half my ice arrows.