Shedinja is always the most banned non-Uber Pokemon in OMs. I'm guessing for this one it's because of:
Shedinja @ Focus Sash
Ability: Wonder Guard
EVs: 252 Atk / 4 Def / 252 Spe
Adamant Nature
- Endeavor
- Shadow Sneak
- Sucker Punch
- Will-O-Wisp/Toxic/Trick
I mean is that too...