>>33663500I'm pretty sure someone else has the links (because i don't) but basically, that's not how it happened.
What happened is that they were nearly going to enter the XYZ part of the anime and director already knew that Frogadier had to evolve into Greninja, but Ash's lack of megas made it so that they needed something else for him to be able to realistically battle with them, so they went to GF HQ to ask if they could figure out a way to make Greninja better, whether a mega or otherwise. What they gave them was pretty much Ash-Greninja, so they went with it.
