Drednaw @ Life Orb
Ability: Swift Swim
Nature: Jolly (+Spe, -SpAtk)
EVs: 252 Atk, 252 Spe, 4 Def
Swords Dance- In the rain you’re already really fast, so Rock Polish isn’t needed
Liquidation- STAB, super strong in the rain
Crunch/Earthquake/Megahorn/Superpower- Coverage, coverage, unreliable coverage, or stronger coverage with recoil
Stone Edge- STAB
It’s pretty simple. All you gotta do is live a turn to dance with swords, then sweep with sharp rocks and your teeth. Though first you need a rain setter like Pelliper with a Damp Rock. Switch into this thing as soon as possible. Swords Dance so you get to +2. With Swift Swim, you’ll be out speeding a lot without the boost from Jolly. Liquidation is boosted by the rain and STAB while Stone Miss is more STAB. The other slot is your choice, really.