I always thought Elephants were one of the strongest
and smartest animals on this earth.
I saw a special once, how elephants are a family,
and how they protect each-other, they actually have a sort of gravesite areas for their dead.
(just like humans)
As which one would win in a fight?
The hippo's jaws are huge, but the elephant has
tusks.
I bet you could contact your local zoo, and maybe
they might have an answer.

My vote is for the elephant!