Who would win a fight 2 black bears a grizzly bear and a polar bear?

It's likely that the polar bear might win the fight. 2 black bears would first go for the grizzly bear and work together to swat that thing to death, but a grizzly bear would also fight back. If the grizzly bear did this, it might have a chance to win, but it could get seriously hurt. Then, the polar bear could kill the injure grizzly bear by biting that thing on the throat.