If your Zygarde has higher attack power:

-Dragon Dance
-Extreme Speed
-Earthquake
-Dragon Tail/Outrage


If it has better defense:

-Coil
-Stone Edge
-Earthquake
-Dragon Tail/Outrage


You can also swap out the first two moves for Rest and Sleep Talk, but that's a bit slower to pull off.

Just don't expect Zygarde to perform as well as Garchomp or Dragonite: Its stats are a bit too low for it to sweep like they do.