It's not native. Mega forms require special items. It's been implied that these items won't be found in game normally.
Also Mewtwo evolving is not on par with Mew as a starter or evolving into a completely different pokemon.
Mega forms is a ridiculous idea. Why take pokemon that are already powerful, and give them another form to make them more powerful? Does Mewtwo, arguably the most powerful Pokemon ever conceived (next to Arceaus), really need another form? Why not instead of giving him a new form, give him the armor that he had from the TV show that let him focus and make his powers amplified?
The point I'm trying to make is that, though it will be difficult to find these items, people will still find them, and it won't really matter, and if you have the action replay code, you can get it anyways. If the items are given away at events and stuff like that, so it's very limited, my point is moot, but the fact still exists that some things shouldn't be changed. Mewtwo was a beast, an absolute monster in the terms of raw power and base stats. Giving him another form, or even an evolution to make him more powerful goes against what the idea behind him was. He was an experiment gone wrong that was a clone of the next most powerful pokemon, Mew. Hence my statement of Mew being a starter.
And last time I checked, having forms that you can go in and out of at will was some shit Digimon came up with a long time ago.
what do you want them to do
just change locations?
I don't care if it's a new location. I'd like to see something new for once. New music. Cool. Character customization. Really cool. Adding a fairy type and giving pokemon that are already powerful an insane boost in power? Pointless. At least go back to where it all began and actually have some references to what happened in past games. Just once, I'd love to see Gary make a return with some insanely powerful pokemon, or Red to make a challenge at the Elite 4 once you beat the champion. Or even including you into the game. Once you beat the champion, you can fight the elite 4 anytime and have to take on random challengers that the game randomly creates. The Elite 4 will send you a call on pokegear saying you have a challenger or some shit. Something to make the game more inclusive and not have the same champion after you beat him 10 times already.
Adding new Pokemon? great. Adding Powerful pokemon? Great. Having like 30+ legendary pokemon that are catchable in the game? Retarded. Legendary means Legendary. Something of legend is something that is limited. Why make so many legendary pokemon? Why? Does every game need a new inclusion to the group? Why not just wipe the slate clean and have none of the old pokemon in the next game? Have them able to be traded in from compatable games, sure, but other wise never seen in the game outside of references or paintings or some shit.
And what about all of these criminal organizations in this game? What is this, Reservoir Dogs? How about a game where all of them just get sick of each other and start to rage war on one another, and stuff starts to get rough for the pokemon world and you have to team up with Red, Silver, etc to take them all on since they've beat them before.
I'd pay to play a pokemon game with all of that stuff in it. I'd gladly fork over the $50 to play some shit on that level.