Easiest way to make an "OC" is the fanfic way.  Rip a totally different franchise and adapt it to the one you're writing for.  So maybe I'll make not-a-saiyan named Melon, er Melon-y.  Yeah, Melony Loch, as naming my character Melony "body of water" sounds like it fits the time travel theme.  Not sure why. :hehe
No, Melony Ness, and make her scottish.  Yeah, and her power is that when she recovers from fatigue or injury, her body reinforces itself greatly.