I dont know, he did not specify what type of bear, if it was a koala bear, I swear those things are nasty... JK
Now a little more serious: after doing a tiny bit of reaserch... THE GRIZZILY WOULD OWN THE GORILLA!!!!! Ok the average male silverback gorilla is like 500(180kg for you little people outside of the US!) pounds, it has no claws but it muscular and has large teeth. However the grizzly is from 800-1200 pounds, is just as muscular as a gorilla, maybe not as smart or nimble, has teeth, AND CLAWS! ok I will make a scenario:
The bear and the gorilla charge at eachother from both endzones, the gorilla attempts to ram the grizzlies large chest with his shoulder but the grizzly swipes the gorilla in the face with lots of force, the gorilla spins to the side, dazed and cut badly. The grizzly charges down and barrels down the gorilla, but the gorilla dodges the grizzly as little, the gorilla catches thegrizzly off balance, and bites the grizzly on the side, the grizzly turns a bit and digs his claws into the back of the gorilla, and with overwhelming force slams it onto its back. after that the grizzly just pounds on the gorilla and naws him to death.
A sad but entertaining ending.........................