I'd be skeptical if it weren't on Serebii, but the new issue of CoroCoro has been scanned and we now have:
New Pokemon
Gogoat's Grass-type pre-evolved form Meekuru (Jp), Normal-type Digging Pokemon Horubii (Jp), and this generation's Pikachu clone, Electric/Fairy-type Antenna Pokemon Dedenne (Jp). The screen in the lower left is from a place called the Super Training Facility.
MegaEvolutions
This one's a doozy, whether these are actual evolutions (which would mean previously unheard-of 4-stage evolutions) or simply alternate forms I do not know, but the following Pokemon will be in the game:
- MegaBlaziken, with the ability Speed Boost
- MegaLucario, with the ability Adaptability
- MegaAbsol, with the ability Magic Bounce
- MegaMawile, with the ability Huge Power; both it and Mawile have also gained Fairy as their second type
- MegaMewtwo, with the ability Insomnia
- MegaAmpharos, with the ability Mold Breaker and also gaining Dragon as its second type
They are evolved/changed by a process known as, appropriately, "Mega Evolution", which
could be the process mentioned when Pangoro was revealed. A "Mega Stone" is mentioned, but not much more.


The
first event for X&Y will be the distribution of a Torchic from October 12th to January 15th holding the "Blaziken Knight" item. It can be evolved into MegaBlaziken.

The girl above is Koruni (Jp), a Gym Leader who teaches you about MegaEvolutions.
More information as it is revealed and translated. These are all literal translations from Japanese and are subject to localization changes.