Decidueye @ Fightinium Z
Ability: Long Reach
EVs: 16 HP / 252 Atk / 68 SpD / 172 Spe
Adamant Nature
- Low Sweep
- Spirit Shackle
- Roost / Substitute
- Leaf Blade
Probably the most time I have ever spent making a set for one of these but wow.
Alright, so the key part here is Low Sweep and Fightium Z. This allows Decidueye to lure in all the dark types that resist it's grass STAB as well (par Muk-Alola). Leaf Blade and Spirit Shackle still act as your STABs. Roost allows you to keep Decidueye healthy throughout the match. Substitute acts as a way to avoid stray Sucker Punches, Toxic's, or get a free hit off on something. The Z is usually intended for darks such as Hydreigon and Bisharp, but it can dent Rotom Heat, Snipes Empoleon (questionable on whether this thing would actually stay in varies on the matchup), and either makes Mamoswine extinct again or makes it wish it was.
Now for the EVs. 16 HP EVs make sure that Decid lives non-specs dark pulse from hydreigon from full every time. 252 Attack is obviously so Decid can hit as hard as possible. 172 Speed hits 219, which is enough to outspeed all non-scarfed Hydreigon at -1 speed. The other 68 SpD EVs are thrown there to make it more specially bulky, allowing it to eat 2 Crit HP fires from Amoongus and eat an unboosted Z Psychic from Celebi after rocks. Long Reach prevents Rocky Helmet Damage, which is always nice.
So Yea, in summary, this set is the most niche thing I could've spent my time making, so I hope you all enjoy it.