Gogeta is the resulting fusion of Goku and Vegeta, when they perform the Fusion Dance properly. His voice is a dual voice containing both Goku's and Vegeta's voices. He has ability of both Goku and Vegeta and also has his unique moves.
Goku (GT) is an alternate version of Goku who appears in the Dragon Ball GT series.In the GT he is turned back into a kid after a wish from Dark Star Dragon Balls. He also has the ability to transform into Super Saiyan 4.
Baby is the last survivor of the Tuffle race who is rebuilt by his creation, Dr. Myuu as a Machine Mutant to exterminate the Saiyans and restore his kind by controlling everyone on Earth. He takes over Vegeta's body to further his ambitions.
Gogeta Super Saiyan 4 is the resulting fusion of Goku and Vegeta in Super Saiyan 4 transformation, when they perform the Fusion Dance properly. This fusion lasts shorter than normal because of the high KI usage of Super Saiyan 4.
Born Kakarot, Goku is a Saiyan male originally sent to destroy Earth as a baby. However, a head injury alters his memory, ridding him of his initial destructive nature and allowing him to grow up to become Earth's greatest defenders.
One of the most powerful and talented martial artists on Earth. Krillin is courageous and faithful. He had a brief rivalry with Goku when they first met and trained under Master Roshi, but they quickly became lifelong best friends.
A former desert bandit, Yamcha was once an enemy of Goku, but quickly reformed and became a friend and ally. Brave, boastful and dependable, Yamcha is a very talented martial artist and one of the most powerful humans on Earth.
Master Roshi also known as the Turtle Hermit and God of Martial Arts, is a master of martial arts, who trained Gohan, Ox-King, Goku, Krillin, and Yamcha. He has a sister named Fortuneteller Baba. In his youth he was simply called Turtle.