Dont forget, the only thing Dead Cell had for them was vamp, cuz he "cant die". but Psyco mantis could just completely destroy his psyche, so it makes no difference. besides, Raven could just turn him to swiss cheese, and even is he "lived", he would be a pile of hamburger. And Solidus was beaten by Raiden. need i say more?
I think the Cobra Unit would put up more of a fight. but if you can overpower Volgin with an AK (as i did) then i think Raven could take him easily.