>>48108159Hippo's are nightmares incarnate but there are even basic Pokemon that would be able to defeat them, whether through bypassing their physical defenses entirely, attacking their brain or soul, using their own strength against them, crippling them with burns and toxins or wearing them down with rocks and sand and spikes, or using their aggression against them. Hippos are very physically durable, but they would be unlikely to have much protection (if any at all) against the more magical or supernatural attacks and abilities.
And no matter what they do, there's one specific Pokemon who can absolutely curbstomp every single African Death Horse that dares to challenge it's might.