Ignoring the Super version, we'll go with the one from Dragon Ball Z, maybe the Bojack Unbound film at the latest (making him in his late teens, early 20s at the most).
So, what team(s) would he join? Whom would he befriend?
I chose Future Trunks, as unlike about all the other Saiyans, he doesn't get blinded by pride or arrogance and is actually quite pragmatic in comparison, and actively aids people in helping them and in protecting them.