>>536275678
>Isn't Nox one of those OCs from Fusions?
Yep. The "Battle-Enhanced Majin."

>How'd that even happen?
During the Quest's Black Star Dragon Ball Hunt, a rogue Machine Mutant (named Mugen) was introduced as a sort of "neutral party," one that didn't care about Myuu's or Baby's plans and was more focused on going around the universe gathering up strong, prized, cool, and/or rare fighters. Ledgic got picked up by him down the line, and Nox was already among his group (among some other Fusions originals). Mugen had them enter in the Mifan Tag Tournament both as a way to help them train and try out new skills (Nox especially enjoying the variety on display) and as a recruitment drive, seeing if he could find any more fighters willing to join his group (Nappa and 16 being among those he wanted to scout out).