Don't get me wrong, I'm not denying that the evolution methods would be easily doable. However, the mega evolutions will not be inseparable to their pre-evolutions either, thus they'll need to be added into the database before their pre-evolutions can overarch to them in the evolution chain. Since these evolutions will be incorporated into the new-generation subsets, however, they'll likely be on the back-burner while previous-generation Pokemon still need to be databased in—moreover, regions still need to be added for their respective generational subsets (3rd and 4th-generation Pokemon already in the database).