I just finished watching the four episodes of Pokemon Origins (it was awesome by the way) and it included mega evolution, so I'm assuming that it was made in 2013(?) ish. But when exactly was it made?
Pokemon Origins was an adaptation of the old Red and Blue Pokemon games. All 4 episodes were consecutively broadcast on TV Tokyo in Japan on 2nd October 2013, 10 days before the release of the Pokemon X and Y 3DS games. The English airdates were in late November of the same year.