Wait hold on.
Is that Professor Oak in the Manga Adaptation comic, the one with the new character?
I mean I wish it was easy to just say that it's the new character....BUT they have different hairstyles and they look slightly different. It's a one off pane if it is Oak, so I guess it's likely if it is Oak, he has relevance to this new character and that's why he's there, but I could be wrong.
I just don't quite believe that it's the new character, since again they do look slightly different, but I guess that could be how the Manga adaptation was done. Like how Majin Buu in Dragon Ball Z, could morph his face in a "pretty boy- type character" something like that.