Doing this Goku became the most powerful being in the universe. Shortly after this encounter he met Trunks who fortold the future in which Goku would die and Cyborgs created by Dr.Gero (C-#20) would reign supreme. But Goku didn't try the easy way out by killing Dr. Gero before he made the Cyborgs. Goku trained in anticapation of the Cyborgs to Goku it was another obstacal to leap over. Goku helped train his son Gohan for the first time in hopes that he would become a mythical Super Saiya-jin also but not only did Gohan achieve Super Saiya-jin Gohan acheived a new level Super Saiya-jin level 2. With help from his father and C-#16 Gohan Transformed into SSJ2 and defeated Cell with a Super Kamehameha beam. Goku next challenge was against a ruthless evil called Majin Buu with help from Vegeta and all the Earhtlings he defeated Buu with a giant Genkai Dama (Spirit Bomb). Goku has defeated many other characters in the various Dragonball/Z/GT movies such as: Terlus, Broli, Slug, Bojack and a world of others. Goku unfaltering spirit is what kept him going the whole time even after he was turned into a child by pilaf (starting Dragonball GT (GT stands for Grand Tour) in which Goku, Trunks and Goku's grandduaghter Pan searched the universe for the ultimate dragonballs to save earth. In this journey Goku, Trunks and Pan met new friends and new foes. At the end of Dragonaball GT we see a young Goku and Vegeta Jr. in a Boudokai Tournement and a very old Pan and Goku standing back in the corner. Pan tries to catch him but she couldn't as Goku flys off into the sunset he has acheived the highest power we Dragonball/Z/Gt fans know of by having all seven dragonballs implanted into his chest and therefore kinda becoming the ultimate fighter/being.