A Japanese trailer has been going around in the last few hours that at one point shows the front cover for this month's edition of CoroCoro. The cover detailed that a brand new Pokémon, known a Magiana, would be revealed within this month's copy of the magazine.
Classified as the "Man-made" Pokémon, Magiana is said to have been created by human hands over 500 years before the present time and has a metallic body. No information about its type was revealed (though there are rumors it may be at least part Electric, and its appearance suggests steel type). It is stated to appear in the upcoming movie - pursued by Volcanion which, apparently "knows its secret". What that means is anybody's guess at this point.
Magiana will more than likely be the first of a seventh generation of Pokémon, although it's likely to be a Zorua situation wherein the Pokémon is revealed and part of the next generation but the games don't officially move to a new region etc. for a bit yet. This is especially likely in that all signs point to the next Pokémon game being a third game set in the Kalos region like Pokémon X and Pokémon Y.