I think we've run a bit off topic now. The original question was asking about main characters or cool co-stars. Random people who appear for maybe one episode can't be considered co-stars.
As for why DBZ gets away with the stereotypical design, I don't think the reason they have those lips is because of black face. I've seen Asian characters drawn with round fat lips too. Most bozoku (a term defining the type of manga or anime character who define what a 'punk' looks like. Typically manga. Examples are Kuabara from Yuu Yuu Hakusho, binbou from Excel Saga, etc.) are drawn with the lips to sort of indicate they don't have much intelligence. Since leaving your mouth open and lips shoved outward makes one look pretty silly.
Then again only one sure-fire way to be absolutely sure if those DBZ character designs are based on black face or not of course is to ask Akira Toriyama.
