None of this has been confirmed by Nintendo yet, so it's questionable how much of it is true. I just wanted to summarize and put the information into an easy-to-read format. I don't think I missed anything, but the link is right below if you want to double-check.
Pokemon Evolutions: * Chespin evolves into Shinnut at 18, then Chinken at 36. Chinken is defensive with armor and long spikes (Grass/Dark). * Fennekin evolves into Kinduples at 18, then Feuensis at 36. Feuensis is a large fox with a necklace of will-o-wisps (Fire/Psychic). * Froakie evolves into Ribburai at 18, then Crokssin at 36. Crokssin has the appearance of a ninja (Water/Fighting; who else is naming theirs Jiraiya? =D). * Litleo evolves into Blazic (Fire/Poison) at Lv15, then Mantiroar at 32 * Helioptile evolves into Solaragon (Electric/Dragon) at Lv 35 * Noivern is evolved from Screeclaw (Lv30), then Whyrill (Lv45) * Fletchling evolves into Talonflame at Lv14, then Scorchawk at 30 * Swirlix evolves into Candilix (Fairy) with use of a Moon Stone * Spritzee evolves into Apothingo (Fairy/Flying) with use of a Moon Stone * Clauncher evolves into Cannoclaw (Water/Electric) at Lv28 * Skrelp evolves into Weeslep at level 28 * Mawile, Sableye, Farfetch'd, Dunsparce and Quilfish are getting evolutions * Miltank, Tauros, Throh, Sawk and Audino are getting pre-evolutions. * Flabebe has a 3-stage evolutionary line.
Kalos Region: * After visiting Lumiose, the player is directed to the west coast, then doubled-back to the east. * Team Flare's headquarters is located in the desert. * The Pokemon League is the castle near Vaniville Town. * The story is not based on or around Yggdrasil (sadness). * Gym Leaders are Viola (Bug), Danica (Fairy), Clement (Electric), Grant (Rock), Jet (Flying), Petunia (Grass), Blaise (Fire) and Lilith (Dark). * Elite Four and Champion are Elizabeth (Bug?), Charles (Psychic), Louis (Ground), Isabella (Ice) and Sycamore (Mixed). * Sycamore uses the fully evolved forms of all three starters, Noivern, Flabebe's evolution, and an Electric/Dark cheetah. * Roue 1 contains Fletchling and a new groundhog Pokemon. * Santalune Forest is home to Spewpa, Scatterbug and Pancham. * Team Flare is taking advantage of Pokemon and manipulating sources of power to make money.
New Pokemon * Approximately 130 new Pokemon * Mewtwo has two new forms: the form featured in the movie is its "Y" form with high speed. * The last title legendary beside Xerneas and Yveltal is a Poison-type snake. * There's another trio of Fairy-types based on nature: Fire, Ground and Water. * There may be an event legendary that's Fairy/Flying to go with the previously mentioned trio. * There's a Nymph Pokemon. * There is a 3-stage Water/Psychic dolphin line. * There is a 3-stage Fire/Bug fire ant line. * There is a 3-stage Dark jaguar line (possibly ending with the Electric/Dark cheetah?) * The psuedo-legendary is a Fairy/Fighting minotaur called Minobaste with an astronomical Attack stat. * Unnamed groundhog found early on (this generation's Ratatta, no doubt; possibly Normal/Ground?)
Miscellaneous: * None of the legendaries are stronger than Arceus. * No new Pokemon fusion effects. * About 30 new items. * The pace is fairly balanced and gym battles are moderately difficult. * The 4th gym leader is especially difficult. * Fairy is SE against Dark and Fighting, and weak to Poison, Steel and Ice (yayness!). * Fairy Wind is the same as Ancientpower and Silver Wind (60 power, may raise all stats).
Playing) Fire Emblem: Awakening, Guild Wars 2 Waiting) Pokemon XY
A Mawile evolution is the only thing that I really want. :I I'm not too optimistic about these rumors, though. It really seems like someone just put together a list of what everybody wants and expects from the game and gave them all obvious names.