Bonzo does not like Ender and here are some reasons why.

Ender isn’t just your average launchie, he is better than most of the older kids. Soon after becoming a launchie he got put into a army, the salamander army, not many launches ever get moved to an army at this young. His leader was Bonzo and Bonzo wasn't happy to a young launchie as a new soldier of his. He hatted Ender so he decided to trade Ender thinking he wasn't going to be a good soldier whatsoever. After a little time passed Ender got traded to the rat army. After getting traded to the rat army he got a toon, and that toon was dink. And before you knew it Ender was becoming not only the best soldier but the best leader as well, becoming stronger and better than anyone