Mal would have stayed close to Ben as much as she could, and since she can turn into a dragon, would have done so to protect anyone who couldn't fight back.
Jyn has no superpowers or anything but she would have something to use as a weapon and kicked as much ass as she could. Probably met up with Luke at some point.
Shang-Chi did awesome kung-fu shit and also helped anyone who needed it.
Oliver enjoyed this far more than he should because he got to shoot arrows and watch the ghouls vanish. He's weird, I know.