Arrghus

Arrghus has small fry like little cream puffs clinging all around its body. They both guard it and attack, so you can't rush in. The only way here is to pull the puffs off one at a time with the Hookshot and grind them down. Once they are all beaten, Arrghus starts thrashing around the room, so hit it with the spin attack.

It is surrounded by lots of rocks, but underneath it is just a puny jellyfish boss. Use the Hookshot or the like to pull the rocks off one by one. Until they are all gone, the body will not budge. The Spin Attack works better than arrows.