Son Trunks
           Being the son of Vegeta, he is a very strong, well disciplined, and tough warrior. He is trying to keep who he is  a mystery in the Trunks Saga, but later reveals his name. He fuses with Goten to create Gotenks, but he sometimes has to set his ki a little lower so Goten and him can fuse, it makes Trunks feel like Goten is a weak person. He comes to the past to tell the Z warriors that androids are going to come and they need to prepare. He was the first saiyajin to become Ultimate Super Saiyajin. Which makes your hair longer and gold, your muscles become real buff, and your power is extremely high. He would have to be the 1st strongest  young saiyajin.