You may as well switch to Water and run Mabui, Mei & Tenten if you want to have a decent time in PVP.

If you had Darui you could run iruka, WB Asuma or Mifune, and Darui as a Lightning character, but it kind of looks like you'd be better off as Water especially with Tobirama.

Not if it's a bad team. Usually when you encounter Tobirama he's not a problem because they don't know what to do with him, so he'll be dead before he c*e his mystery.