Board Thread:New on Ben 10 Wiki/@comment-37390956-20181110111416/@comment-28802873-20181117073653

We don't know that, maybe Zs'Skayr is there, but like Shock Rock and Gax, is locked inside the watch. Plus, Zs'Skayr became a villain because he was already evil, he wanted to take over the universe by going inside the watch and possessing the user. If the Omnitrix is on Earth, he might as well follow it, or maybe he's already inside.

Albedo could appear tho, if he ends up arguing with Azmuth sooner. And Glitch can probably help Ben understand stuff with the Omnitrix.

I also think we need Kevin, they've been teasing us so much with so many references and allusions to his OG role