The Bulbul is an enemy exclusive to Four Swords. It is a large, bulbous creature, with a big green jelly-like sphere protecting its body. In order to defeat it, the core must be laid naked, by repeatedly slashing at the green jelly.
In order to defeat it, the core must be laid naked, by repeatedly slashing at the green jelly. However, Link will bounce off as well and send the creature bouncing off in the other direction upon contact. Therefore, using a second Link attacking from the other side is recommended, since the Bulbul regenerates the layers of jell pretty quickly. After about four consecutive slashes, the body will be revealed, and Link must then hit it one last time before it regenerates some more armor.
Their primary attack is contact. Also, they will periodically dash at Link. This makes them hard to defeat, especially when they come in groups of 2 or more, and together with other enemies. They are even harder in single player mode (anniversary edition), because not being able to control both Links at the same time prevents you from bouncing the Bulbul around ping-pong like between players (it is possible, but requires extreme skill), and therefore it usually takes a few tries to defeat it. And with other ones dashing at Link, and more enemies attacking him, they can be quite lethal.