How do Bull Sharks do in encounters with Alligators and Hippos?

People responding to this question are uninformed. 

While uncommon, hippos do occasionally encounter bull sharks. As I'm sure you're aware, bull sharks will sometimes leave the ocean and travel through freshwater river systems. 

An adult hippo doesn't have much to fear from a bull shark. While bull sharks can be aggressive, hippos are also very aggressive plus they're much larger with skin so thick that even a bull shark would struggle to puncture deep enough to cause any significant damage. 

Bull sharks can certainly kill alligators that are smaller than it. It likely leaves large alligators alone. 

Bull sharks are the meanest, most aggressive of sharks. Not likelyto encounter hippos (undocumented) but given they can navigate fresh water rivers, the shark will kill alligators.

Bull sharks account for most of the shark/human encounters, attacks, bites, and fatalities.

Bull sharks are known to swim up rivers for hundreds of miles and could encounter alligators there .  I know of no attacks on record but it would likely happen under water and not be witnessed .I don't know if that could happen in hippo territory .

That all depends on either animals size

Hippos do not go to beaches, even though dominant male hippos are known as beach masters. Alligators are freshwater species, although they may have to go to brackish water during drought seasons. They too are unlikely to encounter bull sharks. Bull sharks are more likely to meet crocodiles than alligators.