Decidueye @ Normalium-Z / Grassium-Z
Ability: Overgrow
EVs: 24 HP / 152 Atk / 80 SpA / 252 Spe
Naughty Nature
- Work Up
- Spirit Shackle
- Leaf Storm
- Sucker Punch/Leaf Blade/HP fire
Fairly customisable EV's depending on what you actually want the set to deal with. Normalium-Z for a +2 Attack / +1 SpAttack Work up, or Grassium-Z for a free Z-Leaf Storm.
80 SpA EV's is a benchmark to allow:
+1 80 SpA Decidueye Bloom Doom (195 BP) vs. 252 HP / 100 SpD Eviolite Gligar: 280-331 (83.8 - 99.1%) -- 75% chance to OHKO after Stealth Rock
but EVs are highly customisable for whatever threats you want to deal with, since gligar isn't exactly going to be able to do much to a decidueye in the first place, just chose it as an example of something with decent spdef. HP ev's allow you to survive a knock off from Krook at full.
Sucker punch / Leaf Blade / HP Fire can be chosen depending on what you want to deal with, with leaf blade allowing you to deal with blissey, Hp fire allowing you to ohko scizor and sucker punch to deal with gengar / latias (need the +2 from normalium to ohko latias after rocks though, but can't kill you from full if you just spirit shackle instead with grassium).