Rain
Pelipper @ Heavy-Duty Boots
Ability: Drizzle
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
- Hurricane
- U-turn
- Roost
- Defog
Swampert-Mega @ Swampertite
Ability: Damp
EVs: 252 Atk / 4 SpD / 252 Spe
Adamant Nature
- Liquidation
- Flip Turn
- Earthquake
- Ice Punch
Urshifu-Rapid-Strike @ Choice Scarf
Ability: Unseen Fist
EVs: 252 Atk / 4 Def / 252 Spe
Adamant/Jolly Nature
- Surging Strikes
- Close Combat
- Aqua Jet
- U-turn
Pelliper, while not being able to fit all moves is still able to treaten mons such as Mega-Venasuar, Swampert is the definitive swift swimmer with an immunity to electric, and the ability to pressure them with earthquake and switch out with flip turn. That's the key of this. It's bacically a hit and run and a smash and grab at the same tim, we got the main runner Pelliper, and the Swampert and Urshifuhas the ability to steamroll teams with a rain boosted assault.