One of my speculations is that in the trailer Chespin uses a dark move, Fennekin uses a psychic move and Froakie uses a fighting move. So that means that Chespin could be Grass/Dark, Fennekin could be Fire/Psychic and Froakie could be Water/Fighting.
I mean if this is true then I will be happy. I'm getting both X and Y so I'll be getting Fennekin on X and Froakie on Y.
(I'm sorry Chespin :[)