Everyone who said that Pokemon appear only in the movie before the new gen... you were wrong. In Pokemon the First Movie, in the Pikachu short, Snubull and Marill. In Destiny Deoxys, Munchlax was introduced. In Lucario and the Mystery of Mew, Mime Jr and Bonsly.
If this will follow suit, then this is going to have a new Pokemon. At least if the HGSS season is just a season like Battle Frontier.Theory posed, go ahead and rip it apart.