Hi there. So finally after some convincing and stuff, I'd figure to share some insights in the AG meta. Time to leave my two cents, eh?
So first, let me share my insights on the ever-so-deadly Keyspam. I've been trudging along the thread and found Numel as a check. Now, to alleviate this, I'd like to vouch for the viability of Magic Bounce users like Espeon (the Mega slots should rather be used on MRay imo) and Magic Coat users like, say Deoxys-S and Smeargle. Now, the Mega I found most usable for this purpose is Mega Diancie with some Steel-type resists and all, as Mega Diancie provides you with an answer to Mega Rayquaza. The Mega slot could be used to counter this playstyle, so maybe that's up to preference.
Second is, the Smog webzine advocates the mention of Arceus spam, meaning 5 Arceus and the godly Mega Rayquaza. Let me share that this playstyle has pretty much no counters and hard stops if you pack the right coverage, as you can run things like EKiller on one variant, and maybe a special-attacking Arceus on the other. I like this playstyle too, as it brings massive uncertainty and coverage to the user, as well as countering the would-be counters. I'd love to see this style grow.
Third, the Evasion x BP chains I'm hearing about. I'd say to take down these teams, pack something like, say Klefki or Prankster Sableye. Or maybe some heavily offensive Pokemon like Mega Rayquaza, even. Suggestions may be things like, Safeguard support and other stuff like Haze Darkrai and Perish Song Arceus and Murkrow.
I hope I shared some insights and stuff as to deal with common styles and stuff. I guess I'll linger around to see how the metagame develops with the help of the users here. Cheers!