Trailer is out:
https://www.youtube.com/watch?v=TuuuiIKHeYgTranscript (Incomplete Mewtwo - M2, Narrator - N)
>M2: I have arrived.>M2: What you are about to face is not a dream.>Everyone: Mewto!?>M2: Behold my powers!>M2: I am the strongest Pokémon in the world. No, the strongest being.>M2: Say, to all of the living things...>M2: What significance has your birth? What is the true reason for being? >N: Mewtwo's hatred towards the humans gave him powers once again!!>Ash: It's not gonna end like this, Mewtwo! We won't let it! 