I'm concidering doing a DB roleplay around the idea that somehow other Saiyans come to the DBZ world.  The main way I'm thinking of is that after the Buu saga (but before Super because I've only watched a few episodes) Trunks is doing a geneology project for school so he and Goten wish back their Grandfathers.  While Ox King and Dr. Briefs are still alive, King Vegeta and Bardock (and maybe "Grandpa" Gohan depending on how the wish is worded) come back and appear on Earth.  Bardock can at least go SSJ, but the other two are weak.  They go into training, while King Vegeta hatches a plan to bring back his people and conquer this world, whether his son helps or not.

Alternatively, they could reinvent the time machine and bring them back with them, or just wish back Planet Vegeta and all of the Saiyans Frieza killed.

Would anyone be interested in RPing this, and which method do you prefer for bringing them back?  I think bringing back the planet would mean that we could play Saiyans.  Otherwise, we'd have to be characters from the show or OCs that join for some reason.