It's from the trailer.
Looks like a giant robot Tyranitar to me. Don't forget that's right after the green-screen set in the trailer, so perhaps the two are connected. Maybe they're making a Pokemon sentai show in-universe?
Anyway, I don't particularly care which Pokemon are added, as long as it's a variety of types and all the generations get a little love. Seeing Buneary is cool, I might use it in a playthrough. Odds are one of my runs will be all-Unova Pokemon, and the other will be a multigenerational mix.