They're just showing Charizard so they don't have to reveal what the new pseudo-legendary is.
Leak related things:
The now-credible-leak-that-predicted-everything-from-the-direct mentioned that some old Pokemon are getting dynamax-specific new forms. The reason he has a Charizard is probably because it was given one of those forms. I mean, Gamefreak wouldn't waste an opportunity to bring Charizard into the spotlight again, would they?
Oh god please fucking don't let this be the case. Charizard is going to be one of my least favourite Pokemon if this happens, already kind of tired of the damn thing. ---