Weapon Master 13 first arrived to Earth to obtain the Omnitrix. He kidnaps John and tries to remove it, when Gwen, Kevin and Julie come to rescue him. He causes the event that splits the Omnitrix into 4 pieces, with a piece given to each of the four heroes. He is later defeated and sent back to space.
Weapon Master later joins the Separatists, utilizing his Techadon Robots for their cause. He appears briefly on their debut, and when he escapes with them. His base is a large cube resembling the Perplexahedron in space. Ultimate John invades the base, and kills him in the end.
Weapon Master 13 has an underground Techadon robot factory down in undertown, when Ryder passed by. He takes it and tries to hack into the Omnitrix, as Ryder's friends come to rescue him. The hacking causes a reaction in the Omnitrix, releasing a feedback wave that scans all the alien DNA in the vicinity.
Weapon Master 13 works for Argit, being his computer expert. He used him to hack into an account of the Forever Knights, which was so sophisticated that even he couldn't hack into it from an external computer. He sets up the meet between Argit and Collectimus.
Weapon Master 13 was exiled from the Techadon Empire, and has a warehouse in Under Town. Jane helps Otto break in, to help him obtain the Mark 5 Nanoshift Enabled Exo-Armor.
