Pokemon has officially updated with a new Pokemon, an alternate forme (?) of Mewtwo.
I put the question mark because Pokemon constantly refers to it as a new Pokemon with a familiar look. This may be a completely different Mewtwo, possibly another Mewtwo clone. The Mewtwo in the movie posters have also been replaced with this new Mewtwo forme. Considering past trailers that have had animated segments that where never in the original film (Examples being Zoura taking the form of a shadowed Ash/Satoshi and having a much older/deeper voice, and Lugia being in a shadowed form when Ash/Satoshi was stranded in the ocean, most notably, the trailer following the Arceus movie featured Ho-Oh and Lugia battling, despite Lugia and Ho-Oh having no presence or mention in the Zoroark film).
It is possible a plot device in the film is Ash mistaking this new Mewtwo (which I'm dubbing Mewthree until it's true name/form is revealed) for the original Mewtwo.
Time will only tell. But the more I look at it, the more I like it.

______________________