[Darth Kenshin]

yeah if the Vizards were going to directly help the Shinigami, it would probably be here. Not only are they in a bit of trouble, but there's the connection between Lisa and Kyoraku, and the Vizards real beef with SS is not with these captains (whom they probably got along with), but with the higher ups. Plus, Kyoraku and Ukitake have seemingly good relationships with some of the other exiles (Yoruichi, for example), so it would make the most sense for them to interfere here.

However, I'm still not convinced the Vizards are heading to this battlefield. I think it's more likely they're waiting in the real Karakura Town for Aizen, or having Urahara send them to HM to help Ichigo.