The fight would be over before either landed a claw because their anger would dissipate while their claws were in transit.
They would eventually create a second big bang (sorry evolutionists) and we'd have to start the universe all over again.
I think it would be more amusing if rather than being slow and half hearted about it, they turn into like ninja sloths and its all very fast just because people would go 'whoa! what the?? I thought they were slow' they are...except when in mortal combat
Attenborough could film it over three years or how ever long the fight lasts. Then it could be speeded up to make a two minute film.
Never ending battle
Two lawyers would have come to an agreement before the first low was landed