Not much being revealed about Joyboy. But we do know that his powers are crucial to the Technet and while being one the N-men he demonstrated even more power but vanished upon his own will as he fallen in love with the Red Queen from the Crazy Gang, using his powers he give the insane Red Queen a normal life and his psychic bond with her was also affecting others, Gatecrasher was one them who when insane saying images of Hawd-Boiled Henwy, who question the Gatecrasher motives for creating him and demanded retribution for his stupid death. Eventually Captain Britain defeated the Crazy Gang and Joyboy had no other option but to go back to the Technet shortly after that she was called by Roma to obtained Franklin Richards. The young boy use his power to supercharge his family and easily took on the Technet and they had no other option but to leave.
Joyboy later joined the N-Men when Technet returned to Excalibur.
Joyboy can telepathically detect a person's greatest desire and use psionic powers to fulfill a distorted version of the wish, such as when Shadowcat was unable to phase back to being solid, and Joyboy helped her but made her fat. He also made the Witch-Woman become one with reality. However Joyboy has been overpowered by stronger reality warpers such as Jamie Braddock and Franklin Richards. If Joyboy loses consciousness, his transformations of others are immediately undone.
X-Men The Animated Series
Joyboy, along with the other Technet were seen in just a glance, on the animated series in Proteus, Part 1 (Episode 49)