1x8 - Marvel Disk Wars: The Avengers

While trying to solve the puzzle of Whirlwind's tornado, Tony's mind flashbacks to when he and Nozomu (as well as clumsy assistant Peter Parker) were working on the DISK, and how talking about Nozomu's two sons helped come up with the classification systems, and how the party came into being. In the present, Iron Man explains how every hero in villain is split into one of the five classes, and that every Biocode is permanently locked onto the first one D-Smashed.