>>20685201I found this with a quick google search:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCAQFjAA&url=http%3A%2F%2Fmynintendonews.com%2F2013%2F10%2F24%2Fpokemon-x-y-artist-admits-struggling-with-xerneas-and-yveltal-designs%2F&ei=9ML6U5rpHKO_igLB9IHABw&usg=AFQjCNHajB9w5Kbi0uVFaog_STt1LoqKIQ&bvm=bv.73612305,d.cGE>I was tasked with designing both Xerneas and Yveltal, and I ran into a total wall in the process. So I gave the task over to [fellow art designer Yusuke] Ohmura for a while, and once he made some headway on it, I took it back over to finish it off. So they were a team effort. I’ve designed a lot of the legendary Pokemon over the years, but for whatever reason, it was really hard to come up with the concepts this time around. This was the first time I had to field someone else to get me out of my artist’s block, so in that respect, those are definitely the two Pokemon that stick out the most in my mind for this project.But nothing on Ohmura designing the greninja line. Maybe it was taken from an artbook or something.
I'll keep looking around.