Pui Pui is an evil alien who has fallen under the control of the sorcerer Babidi and aids him in his goal to revive Majin Buu.
Major Story Arcs
Majin Buu saga
He was Vegeta's first opponent when he, Goku and Gohan pursued Babidi to his base of operations. Although he was a capable fighter in his own right, killing Yamu fairly easily and displaying impressive hand to hand combat even under 10x the earths normal gravity, he was clearly no match for the Saiyan prince who kills him with ease.
Super Android 17 saga
Pui Pui-DBGT #42
He made a cameo appearance in Dragonball GT, during the Super 17 Saga, where he is seen escaping hell along with all of the other past villains. He is defeated easily by Goten.