- Voice actor: Michael Haigney (both English and Japanese)
Cloyster is an enormous bivalve with a large rugged shell that features a number of spikes. Six of the spikes, three per side, are especially long and conical. Resembling turrets, they enhance the ability of the shell to protect the Pokémon's soft insides from foes. Cloyster's shell has a gray-colored secondary shell inside its larger purple outer shell. Its "head" and face resemble a very large black pearl, with a pronounced white spike jutting out above its "head." Its face is similar to Gastly, though the two Pokémon are not related. It is has been noted that the nature of the inner contents of a Cloyster's shell are not actually known due to the difficulty of observing them. Its height is 4'11" and weight is 292.1 lbs.
Cloyster possesses incredible defensive capabilities unrivaled anywhere else in the Kanto region. Cloyster’s entire fighting style is focused around its uncanny defense: its shell. Cloyster attacks by firing sharp spikes off of its shell while it keeps clamped tightly shut. It is said to be impossible to open from the outside. Aside from its remarkable defense, Cloyster is also capable of unleashing a considerable arsenal of offenses, mostly including Water and Ice attacks, but reaching to Poison and Dark as well. This Pokémon is generally unmoving on land, though capable of moving quickly only underwater using syphon-jet propulsion much like any other bivalve. It is sometimes depicted as having the ability to inexplicably float through the air.
In spite of its grim semblance and its menacing guise, Cloyster's behavior is actually quite unremarkable. In battle, the cowardly Cloyster clamps its monstrous, impenetrable shell tightly shut so that it may not be forced ajar. It then attacks recklessly and aimlessly in all directions with the random, ballistic fire of the spikes on its shell. This haphazard, hit-or-miss style of attack does not earn Cloyster high respect in the field of tactical gumption or cleverness. Though its personality may be lacking, the grimace on its face is perpetual.
Cloyster live deep under the sea, usually on the seabed or amongst coral and rocks. Their range is basically the same as Shellder's.
- Main article: Pokémon food
A Cloyster appeared in The Battling Eevee Brothers.
Ash battled a Cloyster belonging to Pete Pebbleman during the Indigo League in Fire and Ice. It reappeared in a flashback in Friends to the End. Also, in the latter episode, another Cloyster under the ownership of an unknown Trainer, appeared during the closing ceremonies of the Indigo League.
A Cloyster made a cameo in Pokémon Ranger and the Temple of the Sea.
A Cloyster can be seen in To Thine Own Pokémon Be True!.
A Cloyster appeared in Poké Ball Peril.
Multiple Cloyster also appeared in The Power of One.
Cloyster, Bivalve Pokémon. The evolved form of Shellder. Its shell is incredibly strong and resistant to a bomb. Its shell only opens when it attacks.