Stalfos are large skeleton that wield large maces, dubbed Stalfos Clubs. They are slower than in previous entries, and they swing their clubs around rather clumsily, usually spinning around with them. Once Link does enough damage, its body will shatter to pieces and the head will bounce around the room. After a short period, its body will reassemble and Link will have to start over again.
While the head is bouncing around, Link needs to attack it to destroy the whole Stalfos. An easy way to defeat a Stalfos is by using Bombs when it is whole, which will shatter it instantly. As soon as it shatters, target the head and use the Boomerang to stun it. Once it's stunned, smash the skull with the Skull Hammer to kill the Stalfos.