Hoopa's also yet to be revealed. I think it's going to be just like Arceus and Shaymin in which there was a delay before they were officially announced. We'll likely see it and Volcanion later on, maybe even around when Pokemon Z or w/e is released. Also keep in mind that Hoopa has an alternate form in ORAS, so they're bound to release it soon. In fact, given that Pokemon Bank is meant to work with future games, they might even make it so Hoopa's released in a future gen and happens to be available to go back to Gen 6 (to showcase Pokemon Bank's power)