I soft resetted for a jolly one in my game. I've been testing this set in showdown and I believe this strategy is brilliant.
I'm going to name this set:
TableTurner
Marshadow @ Focus Sash
Ability: Technician
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Spectral Thief
- Force Palm
- Shadow Sneak
- Poison Jab / Rock Tomb
- Spectral Thief (Steals buffs and signature move obvious choice)
- Force Palm (STAB, Technician boost, 30% paralysis chance)
- Shadow Sneak (priority, STAB, Technician boost reliable OHKO)
- Poison Jab/Rock Tomb (coverage, poison jab for pesky fairies and 5 more accuracy + 30% poison chance. Rock Tomb for more power from technician boost, flying coverage and speed stage decrease)
Focus sash can save you from a complete sweep of your team. You can stop a sweeper with buffs by stealing them and using the buffs against them and you don't have to worry really about other priority moves as extreme speed has no effect on you and if you are worried you can just use shadow sneak to move first and one shot them before they can mess you up.
A great set overall and much more reliable than these other sets.