Yu-Gi-Oh! GX episode 87: "Blinded by the Light, Part 1"
Gelgo (ゲルゴ, Gerugo), who goes unnamed in the English version, he is also known as Gergo due to common confusion between "L" and "R", is a Pro League Duelist who participates in the Genex Tournament. Gelgo prides himself in winning many Genex Medallions from Duelists, as shown when he reveals all his spoils pinned to the inside of his coat before challenging Chazz to a Duel. However, he is ultimately beaten by Chazz’s new White Knight deck. His character is based on Golgo 13.
It is unknown what sort of Deck Gelgo has, the only card that was shown was "Marshmallon".