Stranger has showings that COULD make him fall if faced against these guys. But, I am not sure there are enough of those showings to warrant a loss.
Although Validus and Mangog seem to be very close in power levels, I think a win against the Stranger would depend on the use of Mangog's history of terrorizing THE Skyfather and the comments that were made in his early showings.
Because, if the Validus team wants a win here, it will have to go beyond simply strength and destruction feats. I don't Stranger would give a sh**.