Gotenks

Gotenks (ゴテンクス, Gotenkusu) is the immensely powerful result of Trunks and Goten successfully using the Fusion Dance. He is a playable character in Dragon Ball FighterZ, fighting as a Super Saiyan 3.

Background
Son Goten, the secondborn son of Goku, and Trunks, the son of Vegeta, are childhood friends who play and train together. During Buu's rampage on Earth, both boys were taught the secret of Fusion, the art of merging two fighters and their energies together into one stronger fighter. Thus, Gotenks was born; a powerful fighter who can effortlessly attain the power of Super Saiyan 3, but whose prowess is offset by a juvenile mindset and a perchant for dramatics.