putting in characters such as the ones you have listed is sort of pointless.. because they are all weak compared to goku and the rest of them. think of it this way. put yamcha against cell, who wins. or even him with frieza.... no matter what happens no one can beat the bad guys. ya see. i mean... no offense to vegeta but hes even worthless, he could never beat one of the evil villians. He helped yeah but never beat one.
anywho my point is the only real people that would be good to put in are the people that are strong. like the androids, goten not little trunks. captain ginu. people like them. if you were going to do yamcha and all them, you would have to balance them out to all the rest of the characters.
Fire Phoenix