In a fight between the elephant and a hippopotamus, the elephant emerges as the winner. The elephant is bigger and stronger, while the hippopotamus is slower and does not have the same reach as an elephant.
The long reach of the elephant is mostly due to its trunk, which gives it better grasping ability, as the trunk serves like an extended powerful arm. The elephant being much heavier has greater momentum when charging to fight off the hippopotamus.
The huge mouth and the large teeth of the hippopotamus are useful weapons in the fight but the hippopotamus is never in a position to reach any vital organ of the elephant while the elephant can crush a vital organ of the hippopotamus with its feet.