Forgive me if I'm being stubborn, but mega evolution just seems like something we won't get before we get access to the majority of pokemon. I mean, why give us an even more powerful excess when we haven't received the decent scraps? Not even giving us certain valuable items but giving us the most powerful item in the form of a mega stone is just ridiculous. Just look at it logically, if we're getting access to all non-legendary pokemon prior to postgame, then the earliest we'll probably be able to use mega's is postgame.
I honestly don't see that happening until we get an event to get Charmander outside of the beginning.