- Prevents critical hits.
- Multi-hit moves will always hit the maximum number of times.
- Grants immunity to damage from weather effects.
Level 100 Statistics (see level 5, 50, 100)
Although mostly outclassed as a supporter by Ferrothorn and Forretress, Cloyster makes for a surprisingly deadly sweeper in Ubers. Its horrendous Special Defense makes it difficult to set up, but when it does get that Shell Smash off, there is very little that can stop it. Cloyster requires a lot of team support to work effectively, but it does have the potential to become a fearsome sweeper.
Cloyster becomes incredibly difficult to wall after a Shell Smash, as it is capable of OHKOing many premier Ubers walls, such as Groudon, Lugia, and Giratina, thanks to its powerful Ice-type STAB. Icicle Spear is the crux of the set, because with Skill Link it effectively has a Base Power of 125. With rain support from Kyogre, a +2 Hydro Pump can KO many Steel-types who would normally wall Cloyster. Rock Blast obtains an immediate OHKO on Ho-Oh, and is Cloyster's strongest attack against opposing Kyogre.
Team Options & Additional Comments >>>
Cloyster provides a reliable way to stave off entry hazards early-game for teams that desperately need their side of the field clear for several turns. It can effectively lead against hazard setters such as Deoxys-A and Deoxys-S and prevent them from laying their entry hazards on the field. Cloyster's ability to function in any weather (apart from possibly sand, which breaks its Focus Sash) makes it a versatile spinner that can fit onto many team archetypes that need a short-term solution to entry hazards. Cloyster can also set up its own entry hazards thanks to its respectable Speed and offensive presence. Unlike Forretress or Excadrill, Cloyster does not possess the typing or bulk to come into the match over and over again, so teams that need consistent spin support throughout the match should look elsewhere.
Shell Smash is pivotal as it allows Cloyster to outrun Deoxys-S and other entry hazard setters, ensuring that their hazards will be spun away. It also gives Cloyster enough power to OHKO the Giratina formes, preventing them from spinblocking. Icicle Spear is a powerful STAB move that threatens Ground-types such as Groudon and Gliscor even before a boost, allowing Cloyster to lead against them. It can also beat Focus Sash Deoxys-A leads with one use of Icicle Spear, though it should not attempt to set up a Shell Smash on these as they often have Psycho Boost or Superpower, as well as ExtremeSpeed. The last slot is dedicated to an entry hazard, which can be used against foes that Cloyster cannot OHKO after a Shell Smash and doesn't need to worry about spinning against, such as bulky Kyogre. Cloyster will outspeed slower base 90s, which is helpful in allowing it to spin against these threats even without a boost or place at least two entry hazards on the opponent's side of the field. The choice between Spikes and Toxic Spikes is up to you. If setting up entry hazards does not appeal to you, you can go with another attacking move. Rock Blast OHKOes Ho-Oh while dealing heavy damage to Kyurem formes and opposing Cloyster. However, Rock Blast is very situational and your team will oftentimes miss the entry hazard support Cloyster can supply.
Team Options & Additional Comments >>>
Hidden Power Fire can be used on the Shell Smash set to nail Ferrothorn, but should only be considered if Kyogre support can't be managed. Cloyster doesn't really have many options, because Shell Smash sweeping is the only thing it's good at. Cloyster can provide support with Toxic Spikes and Rapid Spin, but Forretress outclasses it. Focus Sash or White Herb can be used to give Cloyster some longevity, but it desperately needs the power a Life Orb provides. A gimmicky Clamp set could be used to get up a lot of entry hazards, but it is extremely situational, as many Pokemon in the Ubers metagame threaten Cloyster.
Checks and Counters
It should be kept in mind that Cloyster is incredibly frail on the special side, to the point where a -4 support Dialga will OHKO it with Draco Meteor after Stealth Rock. As such, pressuring Cloyster with special attackers will severely hamper its ability to get off a Shell Smash. In the event that Cloyster manages to set up, bulky Kyogre is perhaps the best counter to it, because it can take anything +2 Cloyster can throw at it and OHKO back with Scald. Similarly, 252/0 Manaphy can shrug off a +2 Rock Blast and KO back. In the rain, Kingdra can outspeed Cloyster and OHKO it with a special attack. A physically defensive Ferrothorn can just barely take a +2 Icicle Spear and OHKO back with Power Whip. Choice Scarf Darkrai and Shaymin-S can both easily revenge kill Cloyster, although the latter must be wary of Ice Shard. Darkrai also has the added benefit of not being overly troubled by Wobbuffet, who could otherwise trap and kill a Choice Scarf revenge killer.
Priority helps deal with Cloyster very well, so Arceus and Rayquaza make very good checks when running ExtremeSpeed. Scizor is also capable of revenge killing Cloyster after Shell Smash, Stealth Rock, and a few turns of Life Orb recoil. Vacuum Wave users, such as Lucario and Toxicroak, do a fine job dealing with Cloyster as well.