I saw this in the running for OMotM, and thought I'd try to implement it on 
rom. It would probably have been easier as a full mod, but I think I've got it coded as a format. Who knows, I might even have got it right first time, or at least so that it doesn't crash.
		
 
Cool! I know what I'm bug testing now :)
As a bit of a side note, baeloetta makes a comeback with techno blast, psystrike, work up, and blue flare. It could also run a choice scarf set with, say, secret sword over work up, or a specs set... While it's weaker than stabmons poryz, it's still very powerful and has a second stab.
Geomancy Hoopa-c looks like a monster- hyperspace hole, oblivion wing, and steam eruption gives it no shortage of powerful attacks, and that's coming off 150 spa. It also has the notable advantage over other gel ancients of being immune to extreme speed.
Keldeo functions mostly the same, but can now pivot with volt switch, smack the Latis with night daze/frost breath, and still keep secret sword+scald.
Geomancy Diancie might also be neat, but 100 spa isn't much to write home about. It's the only other viable user, however.
Talonflame returns, with its nigh perfect dragon ascent+precipice blades coverage, as well as other nice options like water shruiken, play rough, work up, and diamond storm. It really does miss swords dance and roost, though.
Mega Latias is still gods gift to balance/semi stall, with everything it ever dreamed of- wish, cosmic power, slack off, aromatherapy, willowisp, calm mind, magic coat, taunt- it even gets offensive moves. For that matter, every gen 3 Pokemon is a great team supporter. Yes, even shedinja :)