Cloyster
 

Singles Sets
Cloyster @ Focus Sash
4 HP / 252 Atk / 252 Spe
nature: Jolly / Naive
ability: Skill Link
- Shell Smash
- Icicle Spear
- Rock Blast
- Razor Shell / Hydro Pump

• Cloyster makes for an excellent boosting attacker in GBU singles, becoming very difficult to stop after a Shell Smash. With rain support, it's nigh unstoppable without priority, and Focus Sash allows Cloyster to always survive a hit. Shell Smash's Speed boost means Cloyster outspeeds practically everything in common usage.
• Icicle Spear, Rock Blast, and Razor Shell have perfect coverage together. Hydro Pump allows Cloyster to get past physically bulky Pokemon such as Skarmory, but its accuracy is off-putting. If using Hydro Pump, use a Naive nature.

You might want to slash in a naive nature for when you are using Hydro pump. Cloyster isnt taking any special hits anyways, and its holding a focus sash.