So it turns out that Corocoro will have pictures of the newest pokémon, Zoroark! Information was leaked that made it's way onto Serebii. As it turns out, Zoroark is an evolved pokémon from an entirely new evolution line.
What we know so far is it's a Dark type, and based on it's name starting with a Z it's probably safe to assume it is Z. In that case, it's probably also ok to assume that the movie will be similar to the Lucario movie in that it will revolve more around a strong, but not actually a legendary pokémon.
For the full info, go to Serebii's 5th Gen pkmn page!