Goten

Goten (孫悟天, Son Goten) is the second and last child of the protagonist of the series, Goku and his wife Chi-Chi, making him a Saiyan and Human hybrid. Goten was created in the series to replace Goku as Akira Toriyama wanted to retire Goku from the series, allowing Gohan to take command. However, Toriyama was forced to bring Goku back when the fans disapproved of the decision to replace him. Goten is Gohan's younger brother, and Trunks' best friend.
Goten's appearance is very similar to Goku's childhood look, including messy, unkempt hair and a playful face. He also wears a similar gi to Goku's, minus the kame symbol, in the Majin Buu Arc. His appearance drastically changes as he grows older, resembling his brother Gohan more than his father as a teenager; he has the same long messy hair as Gohan at a younger age. Towards the end of Dragon Ball Z, Goten is seen with a shaggier hairstyle. Goten also shares the typical Saiyan appetite like his father and his brother. In Dragon Ball GT, his hairstyle becomes spiky, straight, and tilted.

All about goten super saiyan:
1 Goten super saiyan 1&2

2. Goten super saiyan 3

Information from:
http://dragonball.wikia.com/