After the Mega Salamence quickban, the first actual suspect test of the ORAS era involves not another one of the new megas, but rather a Pokémon that got a substantial buff with the move tutors - Greninja. It was one of the best Pokémon in X/Y, but Fairies and Chansey stopped it dead in its tracks. However, with Gunk Shot and Low Kick now complimenting an already decent movepool, that's no longer the case. Of course it suffers from a bad case of moveslot syndrome, but there isn't a single Pokémon out there that can kill every permutation. If you want to get rid of it, you have no choice but to run one or two checks that can only be qualified as shaky (or the wonderfully exotic Porygon2), or lose right then and there. See, the reason why Contrary is probably going to work just fine with Serperior is because it has virtually no moves to abuse it. Giving STAB on every move to a Pokémon that has both blistering speed and a good movepool, while also boasting well-distributed stats with a total worthy of a starter, is just asking for trouble, especially with the knowledge that said movepool would be expanded later on.
The buzz? Don't be silly, this is a formality. Greninja's a goner. Now I just want to go back in time by two years and tell my 2012 self, two years from now a Pokémon's gonna get banned because it gets Gunk Shot, just to see the look on my fance.
Edit: Seems like the considerable majority of anti-ban people in the Smogon thread have a post count in the single digits. Imagine that, total noobs who just bust out damage calcs without any proper context, or worse, say "just use Porygon2", come crawling from the rocks they've been living under to save their OMG KEWLEST POGEYMAN EVAR. Never saw that coming.