Jelonzo did not originate from fanon, and the information on this page may not be entirely accurate to their canon. You may read more about this subject in the context of their canon on the following wiki(s):
“This is Jelonzo, the charismatic clerk that runs the clothing shop. With his uncanny sense for the hottest trends, he’s viewed as a fashion god of sorts by all the young squids in town. He hails from distant waters and has a strange way of speaking that can make it difficult to understand him, but that may be one of the secrets of his success.”
— Splatoon Official tumblr
Jelonzo's basic appearance
Jelonzo is a jellyfish character from Splatoon. He acts as one of the shopkeepers in the game, selling various t-shirts - of the male, female and unisex variety - to the Inklings in his store Jelly Fresh. Despite being a clothing store clerk, Jelonzo refuses to stock pants. This is presumably due to him being unable to wear them.