So, few thoughts on sets, checks & counters (Pokebank):
Aegislash: Uses the standard SD set way too much. Right now bulky ground types are the way to go when trying to get Aegislash out of the way, therefor an Autotomize sweeper set w/ Hp Ice works really really well, as Gliscor and Landorus(-T) are weak to it and an LO-boosted Shadow Ball/Flash Cannon takes care of pretty much anything that isn't 4x weak to it.
Greninja: Surprisingly enough, only ~15% uses Greninja for hazard purposes (although Defog might be a thing to blame). I'm not seeing too much coherence, most people use him as an all-out attacker I guess. Checks & counters is littered with specially bulky normals & fairies and Greninja can't do shit vs them but U-Turn the hell out I guess (Flying Gem Acrobatics still hits pretty hard vs them tho) so there's plenty of counters. Greninja really doesn't seem like a huge issue, all you gotta know is what moves he's running.
Talonflame: Some things that I need to get out of the way: CB is bad, Acrobatics > Brave Bird, Flying Gem >>> nothing, Adamant > Jolly, Swords Dance > Bulk Up, why the fuck would you use Flame Charge or Aerial Ace, Talonflame generally doesn't have the momentum to Roost off SR damage, Tailwind is a safer choice as it allows something else to sweep if Talonflame happens to be walled.
As for checks/counters: The lack of Heatran on that list disturbs me, even if it doesn't have the moves to kill Talonflame right off the bat, he can still use Roar/Toxic and Talonflame needs multiple boosts before it can take on Heatran reliably. Most rock types can counter Talonflame, and with the amount of usage Ttar is getting people tend to have an answer vs Talonflame (which is why it's much better late-game, once Ttar is removed).
Gengar: Hardy:0/0/0/0/0/0 0.842%
???
Other than that, not much to say. Kinda sucks for him that both Aegislash and Talonflame happen to be really good when it comes to revenging him.
Garchomp: Garchompite 35.940%
Honestly surprising, I was kinda underwhelmed by megachomp. Might be just me though. But on that topic:
Fire Fang 37.485%
Fire Blast 10.533%
Sooo if ~36% of all chomps are mega and only ~10% of all chomps use Fire Blast, that means that most megachomps are utterly wasting a mega slot. Megachomp's significantly higher SpA is one of its main boons, and most people just ignore it? I mean, I know these stats should be taken with a grain of salt and shit, but seriously people?
Lucario: Lucarionite 78.289%
Luke's mega gets really significant use, and there's a damn good reason why: it can do so much more than regular Luke will ever be able to do. Better attacking power thanks to Adapatability, MUCH better speed (outspeeding base 110's like it's nothing) and special/mixed sets are viable now! I see basically no reason to even use regular Luke over this guy unless you desperately want a Luke on your team but already have a Mega on your team.
Also, Aegislash seems to be the main counter, probably because many Lukes mindlessly go for Crunch as Aegislash uses King's Shield, but he seems pretty easy to play around tbh.
well that's it for now