Shedinja @ Safety Goggles
Ability: Wonder Guard
EVs: 252 Atk/252 Spd
-False Swipe/Shadow Sneak
This battle strategy has to be used in a triple battle. Go in the battle with a Pokemon that has Sturdy and knows Skill swap(Carbink), then have a Pokemon with Thunder-Wave and Worry Seed(Ferrothorn), then have Shedinja in battle. Turn 1: Make Ferrothorn use Thunder-Wave on Shedinja. Shedinja uses Will-O-Wisp on a Pokemon. Carbink uses Stealth Rock. Turn 2: Forrothorn uses Worry-Seed on Shedinja, Shedinja uses Will-O-Wisp on another Pokemon. Carbink uses Skill-Swap on Shedinja. Shedinja now has Sturdy and Carbink has Insomia. Spam Hone Claws because your 'Sturdy' ability, Paralysis condition, and your Safety Goggles basically just protect against everything. After that, either sweep with Shadow Sneak or False Swipe (your choice) or cripple the foe with Will-)-Wisp.
To explain everything, Thunder Wave: So the opponent won't put a status effect on you. (Toxic, Will-O-Wisp, etc.)
Worry Seed: Gives Shedinja Insomia ability so Carbink can use Skill Swap. You can't Skill Swap Wonder Guard.
Safety Goggles, Sturdy ability, Don't Switch Out: Safety Goggles protects Shedinja from HP-inflicting weather (Sandstorm, Hail, etc.). Sturdy is most important, since Sturdy leaves you with 1 HP when you would usually get 1HKOed and every hit is a 1HKO to Shedinja, Shedinja never loses health. The Don't Switch Out thing is recommended. Entry Hazards like Stealth Rock is the only thing that can now kill your Shedinja. With the exception of Gastro Acid (It disables the effect of the Pokemon's ability. If you found this helpful, let me know and I will be one happy Bacca. :)