Apologies for the harshness of my earlier post. Any of those mixes are really bad and would be complicated to pull off in the first place. Besides the constant tension and high likelihood for something getting killed, containment is an issue. Containing big cats and pachyderms are two very different scenarios. Additionally sufficiently stressed/motivated big cats have cleared barriers thought to be uncrossable. How do you keep the cats from accessing the holding areas of the rhinos/hippo? Any lion falling in a Hippo pool is good as dead. There's just too many ways for things to go wrong and too much complication in even considering attempting it.