Seems like it, at least. It was added to Serebii's gen 6 Pokémon page, and there he says that it's referred to as Mewtwo's Éclair form on the poster that was leaked last week. So, um, how did it go over the heads of so many people? Surely people fluent in Japanese would've spread the news.
Also, Éclair form, huh? That may be foreshadowing for a Psychic/Electric typing (remember the Electro Ball event from a while ago? Suddenly would make a lot more sense), or maybe it transforms into that form by gobbling down delicious pastries? Who knows. What I do know is, this guy looks like a Levitator. Psychic/Electric levitator please!