You can see two two main stars of the new Pokemon movie in this trailer. Yes, you can see both Genesect and Mewtwo in action in the latest Extremespeed Genesect: Mewtwo Awakens trailer.
In the trailer, Genesect attacks Ask and Pikachu but Mewtwo arrives to shield the,. It doesn't last forever, however and Genesect returns to take out Pikachu (poor Pikachu) before Awakened Mewtwo arrives on the scene.
We also get a glimpse of the short movie that will be shown with Extremespeed Genesect. It's called Pikachu and Eevee Friends and it will feature all Eevee evolutions including Sylveon, one of the the new Pokemon announced for Pokemon X and Y.