the whole point of mega is a short-term boost for its power!
Also your idea is just horrible! Pokemon surgery? What is this human centipede?
Well I know but it's just so annoying that currently, even if you do hack a pokemon to stay in it's mega from forever, you can't play with it in Pokemon Amie because they didn't make models for them in there.
I just want to be able to pet my Mega Alakazam while it's in it's mega form :S
Also what's wrong with pokemon surgery, this is a game so it's not like they would feel any pain or anything like that.