Who Would Win?
They'd rarely fight in the wild, but a black bear would probably win. They're bigger by about 50% (200 lb for cougar, 300 lb for black bears), have very sharp claws, stronger bite force and thicker skin.
It'd be a dangerous fight for both and the winner would very likely die to its wounds, too.
Bite force of cougar 350 psi
Bite force of black bear 975 psi
Ill take the meaty paws of the black bear over a cougar. my prediction is the cougar would stand down when the 2 would come face to face if we are talking average size adult black bear vs average size adult cougar.