No, tennis players do not wear cups, but they probably should because the serve comes in very fast and it could really to some damage if it hit you square in the family jewels. (penis and testicles.)
Tennis players can wear just about anything. Female tennis clothes are sometimes full short dresses. They are usually made out of material that absorbs sweat easily. Dresses and skirts will generally...
Probably most male tennis players wear either a jockstrap or some kind of supportive sports undergarment, e.g. compression shorts, jock boxers, athletic briefs, etc.