>>15730240Aegislash is overrated and predictable, but still solid. Its best set doesn't even use King's Shield. A bunch of people using an inefficient set of it online does not a bad mon make.
Klefki as the best bulk among the Prankster users with the best typing with a fantastic support movepool. It's also just as good, if not better, than running Swagger+Foul Play than Spooky Boogy Liepard.
Sylveon is a great Wish passer that isn't setup bait. Good stats and moves for its type, it'll definitely see OU play, even if it settles no less than UU.
Gourgeist/Trevenant have strong anti-meta typings. Gourgeist will definitely see OU play with either a fast or guaranteed (due to bulk) Will-o-wisp+Leech Seed. Most people use Trevenant for a gimmick recovery set, but it has very strong utility on top of its tanky bulk/offense. Trevenant will likely be a dominating force in whatever lower tier it settles on.
The only good thing about Noivern is Infiltrator+dat Speed. Boom Burst is only useful because it acts as a STABed move for things that resist Dragon/Flying short of Steel, for which it has Flamethrower/Fire Blast.
Greninja is also overrated, but it's a fantastic revenge killer, late game sweeper, and is a wonderful lead due to T/Spikes, Taunt, and Uturn.