>>11878018He is saying the new movie poster is not fake, in reply to some user who says the original poster was photoshoped to put the new form over the original mewtwo.
Hiro says that the posters are updated as new information is being revealed. He uses the Dialga vs Palkia vs Darkrai movie as an example which poster only showed "Dialga vs Palkia" initially.
This is kind of how the Eevee short added new characters to the logo when Sylveon was revealed
