Description: Cloyster's main set is one that can sweep most teams with ease; in fact, it's a liability to have a bulky Ground-type when your opponent has a Cloyster. This set is best used on an offensive team, where other sweepers can open up holes in defensive cores for Cloyster to take advantage of. Shell Smash is the crux of this set, doubling Cloyster's Attack, Special Attack, and Speed to threatening levels. Icicle Spear is the perfect move for Cloyster; because of Skill Link, it will always hit five times, effectively making it a 125 Base Power STAB move. Rock Blast offers great coverage with Icicle Spear, hitting Fire-, Water-, and Ice-types for at least neutral damage. In the last slot, either Hydro Pump or Razor Shell is acceptable. Hydro Pump is the preferred option for getting past Skarmory, Scizor, Forretress, and Metagross, since it hits their weaker Special Defense; however, Razor Shell will destroy Tyranitar and Heatran without fail, as they both commonly run specially defensive sets.
Options: Maximum Speed investment allows Cloyster to outspeed Scarf Latios with Hidden Power Fire and Modest Venusaur in the sun, among other things. Full investment in Attack bolsters the power of Icicle Spear, Rock Blast, and Razor Shell greatly. A Naive nature boosts Speed while not detracting from Hydro Pump's power, but if you are using Razor Shell, a Jolly nature is the way to go. If you are not using Hydro Pump, the 4 EVs can go into HP but the remaining EVs can also be thrown into Special Attack to slightly boost the power of Hydro Pump. White Herb is the preferred item on this set, as it restores Cloyster's godly Defense, cushioning it from priority attacks such as a Scizor's Bullet Punch or a Conkeldurr's Mach Punch. However, Cloyster does get some notable KOs with a Life Orb, such as Ferrothorn with Icicle Spear and bulky Rotom-W with Rock Blast. White Herb is usually superior, as Cloyster often doesn't need the extra power and lowering its defenses makes it more susceptible to priority.
Counters: Dual screens are also great support for Cloyster; with Reflect up, Cloyster can survive Jolly Choice Band Terrakion's Close Combat, even after one layer of Spikes. Espeon is a fantastic partner, as its ability, Magic Bounce, prevents hazards or Taunt from being used, which gives Cloyster an easier time setting up. Entry hazard support is also greatly appreciated, as with just Stealth Rock up, Cloyster can OHKO Choice Scarf Rotom-W and Choice Scarf Politoed most of the time. Both Forretress and Ferrothorn have good synergy, but Forretress can also utilize Rapid Spin to aid Cloyster. Another useful teammate is Magnezone, since it can trap and KO troublesome Pokemon such as Scizor, Jirachi, and Ferrothorn, giving Cloyster a much easier time sweeping.
This is a good moveset for cloyster (Pokemon #91) with the skill-link ability/trait, a Jolly nature, and equipped with White Herb submitted by Cybermewtwo. For use in competitive Pokemon battles featuring an Export option and breeding guide.