It's probably from Yveltal's Death/Oblivion Wing. Remember Ash also turned to stone when he "died" in the first movie? Perhaps this is also referring to that for nostalgic reasons.
Really loving the trailer! Greninja is my new favourite Water-type Pokémon so it will be great to see him in action. The trainer also seems to be a ninja. Could this be the big brother of the Frogadier trainer? That would mean the series and movies actually go together, though, so I don't know if TPCi would do that.
I wish I could see it in the movie theatres. Sadly I'm leaving Japan the 7th of July already.
Maybe I'm weird, but I'd actually like for Yveltal to win. I love him so much. I can picture him reigning over a dead world Welp, that will never happen, but I am still excited for the movie.
One thing I noticed is that there's new advanced and updated graphical effects for Xerneas' attack against Yveltal we saw in previous trailers. Nice touch.