This is what I use :
Aegislash w/ Air Balloon
or Leftovers (Adamant nature)
Ability: Stance Change
EVs: 252 HP / 252 ATK / 4 Speed
Moves :
- King's Shield
- Shadow Sneak
- Sacred Sword
- Iron Head
I recently replaced Sword Dance with Iron Head and to tell you the truth, Shadow Sneak
needs Sword Dance IMO. Without a +1, Shadow Sneak isn't going to hurt that much.
So maybe it's best just to use King's Shield, Shadow Sneak, Sword Dance and Sacred Sword with a speed reducing nature. If the Pokemon resists fighting-type moves, get +3 and spam shadow sneak,
The speed reducing nature is good if you want to take hits while you're in shield form and dish out damage while knowing you're safe, but it's easy to predict a King's Shield with this version.
You can also run a mixed attacker or a special attack version with shadow ball and flash cannon, however, I personally prefer a physical attack Aegislash for the priority stab move (Shadow Sneak).