This is pretty much an impractical task. Only twenty-two (XY - Ancient Origins) of the 50 Mega Evolutions (including Primals) have been currently covered, and on the assumption that 3 individual mega evolutions are released per set, of which 5 are released each year, only 15 individual Mega Evolutions will be released each year. That means we need approximately 10 sets, or 2 years, to cover each Mega, which is a bit of an impratical task considering the Gen 7 (and possibly some type of XY sequal) would have been released by that time, either causing a new TCG era and/or new flow of Megas.