These are the top of my head:
Zacian doesn't need Fairy STAB. You can replace it with Close Combat
If you're running Focus Sash Marsh, run Bulk Up instead of Drain Punch, though it's recommended to run a LO set, where you should run Rock Tomb or Ice Punch over Drain Punch. You can also think about replacing Spectral Thief with Poltergeist
You can try running Draining Kiss over Pollen Puff on Calyrex - S. Plus, it really doesn't need a Scarf. Try a Specs, LO or Sash set.
I'm not sure about the Gengar set either, but I really don't use it, so no comments.