Seto Kaiba is a supporting character who runs Kaiba Corporation.
Seto Kaiba role in Generation Duelist! is a support character who runs Kaiba Corporation, and builds Duel Academy for students to learn how to duel and train as professionals. He is the brother of Mokuba Kaiba and step-brother of Tatyana Parham who later on becomes his wife.
Temple of the Sea Arc
Seto Kaiba appears in Generation Duelist! when Shanoske and Tatyana find two Pokemon eggs who were know to have the ability to locate the Temple of the Sea who the Pirate Lord and his gang wanted to seek out to own the power of the Sea Crown Kaiba discovered this and rushed over to Duel Academy to help his friends even though he doesn't admit it. Kaiba was later discovered to be seen with a Kryoge the Legendary Water Pokemon after defeating them he returned to KaibaCorp.
Ikran's F-Zero timeline
He was hardly seen, but he's been mentioned by the main duelists, Yugi and Joey several times. Even when Tinsel saved them from the Battle City island he blew up. He was unable to attend Tinsel and Rick's wedding since he passed on as his spirit ascended after the duel against Diva.