Not sure if this has been discussed yet, but I came across this today and thought I'd share. None of these are for-sure real but I'll post all the information I've collected across the internet.

Serebii apparently posted these 3 momentarily on their website before removing them, along with an attack called Light Of Ruin (I have a screenshot of that, not taken by me, though).

The file is blurry so in case you can't read or are too lazy:

#719
Diancie- Rock/Fairy

#720
Volcanion- Fire/Water

#721
Hoopa- Psychic/Ghost

What I've heard is that the names were trademarked in both Japanese and English and that you can search for them on the GTS by manually typing in the names. They react different than typing in gibberish names- For example, typing in PIKABLU would result in it staying PIKABLU and wouldn't show up on the global search for others, but VOLCANION auto corrects to Volcanion and others can see it on the GTS as something being asked for..

Speculation seemed to be that they're going to be released pokemon either for XY that come out later, or for the 3rd installation of the game. Since there's no datamine for XY yet, I guess we'll just have to wait.

Honestly Diancie having the same typing as Carbink sounds like Carbink gets an evo... and Carbink = carbon, Diancie = Diamond, etc. Carbink is good on its own though so I almost hope this isn't the case because

>Carbink with eviolite