Defeating the Gleerok involves firing the Cane of Pacci at its back, and then climbing onto its back and slashing with the sword while it is rendered unconscious. Gleerok's main form of attack is to spew fire on any surrounding prey or threats. If all else fails, it will submerge itself in its lava pool and cause major disruptions within its abode, including an increase in lava flow and tectonic disruptions that cause chunks of rock to fall from the ceiling. Gleerok seems to hold a same sort of power as the Fire Wizzrobe, as when the Gleerok spews fire, some of it causes Link to run around in a frenzy; the same thing that happens to Link if he is hit by a Fire Wizzrobe's power. Gleerok is most likely an evolutionary offshoot of the Gleeok, or a mutant/mutated Gleerok, adapted to harsh lava-filled environs. Along with this evolution/adaptation, it seems to have lost the ability to sprout multiple heads.
In The Minish Cap Manga, Gleerok was, prior to the battle, cursed by Vaati. Once defeated, Gleerok turns back to its true form, a softer, plesiosaur-like creature. The newly transformed Gleerok then gives Link the Fire Element.
This creature bears an uncanny resemblance to the Pokémon Lugia.