Translation! (MASSIVELY SPOILERISH, Also the rumours are taken from 4chan. A guy called Pokemon Monseiur claims to have early info/access)
-A racing minigame. You can ride pokemon on land, sea and air.
-Gogoat has two versions, the trailer one is a male. There is an unridable female without horns, apparently visible in the edge of the trailer.
-The final evolutions will look like this:
Chespin will look like an (American) football player, with helmet and protection. Fennekin will have large ears that look like bat wings/cape. He looks like a flying Zorro. Froakie looks like a ninja from a Japanese painting.
-There are more new pokemon introduced than in Gen IV.
-Sylveon is Eevee's only new evolution.
-Clefairy, Togepi, Jigglypuff, Chansey, Lickitung, Snorlax, Dunsparce, Audino, Snubbull, Skitty and Whismur, and their evolutionary lines are Fairy.
-Mawile, Absol, Misdreavus, Milotic (not Feebas), Chimecho, Uxie, Mesprit y Azelf are half Fairy.
-Mawile has an evolution with 2 mouths instead of one. Apparently it looks like a horse's tail? It might be a reference to Hastune Miku (?). It learns quiver dance, a bug move.
-Eevee, Mawile, Sableye, Dunsparce, Bannette, Tauros, Heracross, Pinsir, Bisharp, Maractus, Cryogonal y Drifloon have new evolutions.
-Lickitung, Throh/Sawk (shared?) and Absol have pre-evolutions.
-Drifloon's new evolution is an alternative to Drifblim and is ghost/fairy.
-There are 2 new teams, Team Acid and Team Base.
Acid has 'punk rock' motorcyclists who want to experiment on pokemon to create the best one. Their leader is a long haired woman. Their important members are 'admins' and they use poison pokemon.
-Team Base are less evil and more misguided. They wear Tai Chi clothes and want power to protect what is important for them. They steal weak pokemon from trainers to make the pokemon strong. The leader is an old man, (with a muscular white horse?)
-Xerneas and Yveltal represent life and death. Kalos has had numerous wars where Yveltal destroys it only for Xerneas to rebuild it.
-Xerneas represents purity and is Fairy type. Yveltal represents ambition from the sky?. It is dark/flying.
-Two new legendaries. One is dragon/flying and looks like a classic chinese dragon with three forms. The other is fairy /steel and has 3 forms, going from a gold bell with angel wings to a knight angel.
-A new poison/flying legendary based on the 'Zhenniao'. It looks like a green hummingbird. It might be protagonist in the next Pokemon film.
-Xernas and Yveltal will each have a set of three subordinate (might be that they form a trio alongside the subordinate 2) legendaries. Xerneas has to small women-like Fairy/grass pokemon. One is skinny and the other is chunky. They are humanoid and wear a leaf, one is orange and the other green. Yveltal has two dragon/flying pokemon. I think they are pegasi. One has spikes that form a sun on its side.
-There is no third legendary to Xerneas and Yveltal, though there is a water/rock leendary that looks like a giant squid with a head covered by rocks that looks like an ancient city. It also has two subordinate water types which have tentacles and mouths with teeth.
-More legendaries will be distributed by DLCs. It has not been specified whether you have to pay for them. (My guess is they will be like Darkrai and similar pokemon, where you unlock the mission by going online?)
There are different clothes, including an outfit similar to Team Rocket's. Other outfits might be released as DLC.
-There is only 1 fossil, a rock/dragon that looks like a T-rex. You get it similar to Spiritomb, by having a number of players. I think there is a minigame where you play with others and find him in parts (head,arms, tail and legs).
-You can pass over pokemon from 5th gen through a program downloaded from E-shop. You can transfer 25 (in one go, doesn't mention repeatability) and they appear in your pc. You have to buy the pokemon using ingame money/tokens though. This is to stop you transfering high level pokemon when you are a very low level. You can rename the pokemon you transfer.
-The strongest new pokemon are poison pokemon.
-bug, fairy, normal, fighting, ghost, ice, fire and psychic. They have a different order depending on the game version. Bug, fairy and normal are in central Kalos, afterwards the order depends on the game version.
-Progression may not be as linear as in previous games.
The Elite 4 is based on stats HP, attack, defense, speed, rather than type.
Your rival becomes the champion. (Another Gary? Oh yeah!) You have 4 rivals, a childhood friend looking for some bullies, a fat millionaire, a traveller looking for the perfect site. The main rival a hunter that begins as your mentor. His favourite pokemon is tauros, afterwhich he uses its evolution. At the game's beginning a girl follows you aroudn the beginning forest and teaches you the game's basics. She is the Professor's daughter. (Maybe the girl in the trailer screenshots that looks like the female PC?)