Pikkon is a dead fighter and was goku's rival in the after life he also appears in fusion reborn
Paikuhan appeared along with the West Kaio ( Goku is with North Kaio ) on the Grand Kai's Planet. Dai Kaiō asked to Paikuhan to go hell, because Freeza and Cell were causing a great destruction. Goku followed Paikuhan, but Paikuhan defeated Frieza and Cell without any difficulty.
The Martial Arts Tournament (from After Life) begins with competitors from each galaxy. After many struggles, the finalists were Goku and Paikuhan.
After a long and difficult struggle, Goku defeats Paikuhan (Goku uses a Instant Kamehameha).
Later, Majin Buu appears on Dai Kaiō planet. Paikuhan and the other wrestlers thought that Majin Buu was another fighter. Majin Buu defeated each one to show his powers and began to create a sphere of energy to destroy the planet, but Buu stopped when detecting the KI of Goku and Vegeta.
Dragon Ball Movie 12:
Paikuhan and Goku were fighting in another Martial Arts Tournament, but they had to stop the fight because Dai Kaiō ordered them to be up to the castle of King Yemma (the castle of Yemma was having problems). Goku discovers that the problem was a powerful creature made of negative energy. The creature called Janemba. Paikuhan helps Goku and Vegeta (Goku and Vegeta had problems with the fusion).
Paikuhan is a character created for the anime fillers.