The go-to set is the SubCoil set, which looks something like this:
Zygarde @ Leftovers
Ability: Aura Break
EVs: 252 HP/4 Atk/252 SpD
Careful Nature
- Substitute
- Coil
- Dragon Tail
- Earthquake
There is maximum investment in SpD because Coil boosts Zygarde's Defense anyway. EVs can be shifted...