I don't mean making M. Mewtwo EX a dual type like they did with Volcanion EX. I mean making that card a pure fighting type Pokémon. Personally I don't really like the dual type mechanic, though it's a personal opinion that I can't really explain.
You know on one hand I wouldn't mind seeing it. But from a game design perspective and possibly even a play perspective can you imagine how much of a headache that would be. Flying is after all one of the third highest type in the game (behind normal and water I believe). How many cards would have to be revamped for the type? How many would never be revamped, hence drawing people like me to want that to happen? How many other cards have to be changed to accomdate for weakness, some grass and fighting no doubt. Are they weak to water (ice) or fighting (rock) despite the latter also being weak to on the fighting side? Or are they all weak to lightning, hence resulting in a potentially doomed match up like we see with water vs. fire? I mean they can't even make fire weak to anything other than water, it's been that way since Gen 1.
And why just flying? Shouldn't ice get a chance? Rock? I mean where do they stop with that? I mean there are 18 different types, 11 of which are represented if we count colorless as a type (I think it was meant to add some variety to decks and for the longest time was never meant to be considered a type) and dragon despite it's lack of real energy. Another type or two added in randomly might just complicate things for the game.
I mean yeah it would be cool but somewhat unneeded. I still don't quite know why they made dragon it's own type, especially since it doesn't get it's own basic energy. My guess is because they knew fairy would be coming in gen 6 and wanted to have that specific pattern there, which is why dragons went from being weak to itself to weak to fairy. It's just lucky that fairy isn't completely immune to dragon in TCG as they are in TVG.
Yeah, I do think some of the other types should get the chance but I would be fine if they made some fighting, grass and bug Pokemon weak to colorless in the TCG so colorless could at least get some type effectiveness but I want flying to be its own type for at least bird Pokemon so they can hit for weakness since other Pokemon can do so.
I also guess a pure fighting mewtwo would balance it considering how powerful psychic mewtwo is. He just shuts down every other psychic weak Pokemon.