>>29712340>implying Komala won't be a one-off gimmick/shitmon like Farfetch'd, Dunsparce, and most other things that end up in the latter part of any pokedexEven then though there's Pyroar, so you're right. But why would you leave Decidueye in battle against something it can't manage in the first place?
>>29712356True. Trevenant actually has access to moves that cover all of its weaknesses, it's just... Trevenant unfortunately. Decidueye will have a different stat spread than Trevenant (hopefully), so one would hope it ends up being more defensively useful and still has access to Rock/Fighting/Ground something.
Still, not even knowing the BSTs of their fully evolved forms, I wouldn't LEAD with Decidueye. Grass/Ghost isn't bad - you resist everything Dragon does save for Fire, plus Ground and a Normal immunity, and you don't have to worry about Bug and Poison as much as other Grass-types - but you are losing those two weaknesses in exchange for Ghost and Dark.
I won't go so far as to say it'll make OU
because it won't, but there's a pretty good chunk of things in UU that would have a hard time with it if it's bulky enough.