Bandai Namco would love to see Shadow Mewtwo appear outside of Pokken Tournament, but say it’s not their decision to make; the choice is Nintendo’s to make.
In a recent interview with Polygon, producer Masaaki Hoshino outlined the collaborative effort between both Namco and The Pokemon Company that gave birth to the enigmatic version of Mewtwo.
When we were originally coming up with the design, we worked very closely with The Pokémon Company and Game Freak to make sure everything was right. What happened was, we at Bandai Namco had the idea of making a really cool dark-colored Mewtwo, so we had one of our designers take a crack at it and then presented that to The Pokémon Company and Game Freak. They all thought it looked really cool, so then we worked together to brush it up.
Because everyone really liked Shadow Mewtwo, I have a personal hope that they’ll continue to use it, but it’s not really our decision, unfortunately.
Despite his apparent popularity though, Hoshino’s colleague Katsuhiro Harada simply can’t say whether The Pokemon Company will ever decide to make Shadow Mewtwo a canonical Pocket Monster in the series’ main entry continuity. Sadly, he may only ever appear in Pokken Tournament.
For this game, it is kind of a spin-off from the main series. It takes place in this area called the Ferrum Region, which means something like ‘Iron Region,’ playing back into the Tekken connection.
So, within the context of this spin-off, [Shadow Mewtwo] is obviously a canonical character. Of course, how The Pokémon Company and Game Freak decide to use the character is up to them, but I think Mr. Hoshino’s passion for the character might inspire them and encourage them to use it!
With that said, The Pokemon Company gave a simple “no comment” when quizzed about the subject, so never say never. For now though, you can at least see Shadow Mewtwo’s debut in Pokken Tournament when it releases for Wii U on March 18.