Board Thread:Questions and Answers/@comment-11452788-20130702111039/@comment-5846800-20130703005052

Zimvader42 wrote: They weren in the episode "the ultimate sacrifice" for unknown reason. I think that that episode (when all the ultimates try to convince ben to commit suicide to let them free from the ultimatrix) came out BEFORE the first appearance of ultimate wildmutt and ultimate waybig.

They're probably still trapped inside the ultimatrix, but currently, is Azmuth who has it. Correction Azmuth doesn't have the Ultimatrix, he destroyed it after the Final finale of Ben 10: Ultimate Alien, so technically if the Ultimatrix was desroyed, Ultimate Way Big and Wildmutt were destroyed(probably, Azmuth might have freed them before he destroyed it somehow)