Here's Mega Lunatone.

Sadly, this seems to be fake, first the pokemon is lacking black outlines (even on the mega galie/steelix leek pictures you can see them so 3ds quality isn't an excuse), second it has just been sent out into battle (the ground lacks both the shadow and is quite small, not only that but there isn't any HP gauge on the side so UNLESS THE DEMO WAS HACKED INTO THIS EARLY this is more than likely fake) before you can say that "it's just using a move" none of solrock's moves that it can learn start from that camera angle, three Solrock is facing the wrong way, If it HAPPENED TO BE HACKED INTO SO IT STARTED IN IT'S MEGA FORM then you would only see it from it's side and according to the trailers the camera isn't placed in that position to provide the view the "leek" is showing. so yeah…fake…it would've been interesting though…