Mega Genger and Blaziken will likely get banned to Ubers before long. Meanwhile Mawile, Kangaskan, Pinser, and MAYBE Gardevoir will be OU (once people discover how blasted good they are). The rest of the Mega's will be BL.
Meanwhile for the new Pokemon Aegislash and Talonflame will be OU (remember they don't have to be good in practice, just look good to noobs, Talonflame will be OU because "ZOMG PRIORITY BIRD MOVES!" despite the fact it suuuuuucks). Meanwhile Goodra and Barbarcle will be UU, and a couple more will probably also sneak in to UU. The rest of the new Mon will sink in to obscurity because they both look god awful and suck competitively.
Most people play Talonflame badly, but it can be good if you're smart.
If you run... Acrobatics Roost U-Turn *other*
it can do some serious s***. U-Turn let's it get away from T-tar while still doing something about it. Priority Roost can let it get some healing even against electric enemies and makes SR less of a big deal.
That only works on people playing a bog standard tanky T-tar set or playing predictably. The fact they have to switch one way or the other means it's screwed easily, and you can either set up on the switch or predict what they'll send in and smash its face off. --- Official MegaLucario of the Pokemon X and Y boards
If Furfro gets Slack Off, if COULD sneak into UU, but it'll probably sink back into the hellish depths of NU. --- NEVER confuse "excuse" with "explanation", It is one of the worst mistakes people have with their judgement. - NovaeGamer
Greninja will be low OU or UU definitely. Nothing more, it can't take any damage. Chesnaught will probably be UU or RU. Too many weaknesses that are special based. Delphox (as useless as it ISN'T >_>) will most likely be NU or RU. Three priority weaknesses (aqua jet, shadow sneak, and sucker punch) screw it and it has a questionable movepool. Zygarde will be UU. It has dragon dance, but its stats suck. Goodra will probably be RU. Its defense SUCKS.
Those are my predictions. Please note that I know not much about Smogon standards.