Professor Mondo Tatsumi
Mondo is the great scientist who created the suits, mecha, and weapons for the GoGo Five team. Years before he predicted the invasion of the Saima Clan but no one believed him. Forced into exile and ridiculed by the elite scientific community, he secretly developed the equipment. Dr. Tatsumi has built an undersea base in the bay known as Bay Area 55. To save the earth and the human race he paid the heavy price of losing his family. Years later, he had to convince his offspring to help him out with his cause, but they were bitter and angry towards a father whom they believed died years before. Even though he had create an elite team that would save the world, they still believed he abandoned them.

One time to try and show his love for his children he even wears the prototype AntiHazardSuit to save his children from the Saima Clan. In the finale, he surrived alongside his rival when BayArea55 sank beneath the sea from the massive floods caused by Grandiene, and Mondo now lives happily with his family. However, Mondo briefly went out of retirement when he detected Pierre's minus energy. Mondo was instrumental in working with the Timeranger's robotic assistant Takku, in bringing both teams back to the present when they were transported across time due to Pierre's magic as well as bringing the GoGo Five's mecha from the past to the present with the Timeranger's time travel technology, to help destroy PierreBori.

Ritsuko Tatsumi
Ritsuko is the wife of Professor Tatsumi and the mother of the Tatsumi siblings. In 1992, she left to search for missing husband, making children promise to watch after each other and her daughter gave her ringing bell charm. It was her words that always ran through their heads and kept them going in the greatest trialsand tribulations of their lives. "The five of you are one family. When you forget your power, no matter what happens, I believe in you. And, my wonderful children, believe in your father. Family is to believe in each other" were pretty much her last words to them the day she got on an airplane that then crashed. She spent the next seven years at an island hospital in a coma. When she finally became conscious, she remembered dreaming about her children, fighting terrible monsters. She then contacted their house and their friend Kyoko Hayase picked up the call and relayed the message to Daimon and Matsuri. They later called her back. She guided her five children out when they were trapped in one of the Saima hells in episode 42. At the end of the series Ritsuko is living with her family again in episode 49-50.

Kyoko Hayase
A shuttle pilot who is Shou's superior. When the GoGo V rescue her shuttle from a tornado caused by Tornedeus, she is able to recognize Shou's voice on the communications system. This is because the shuttles communications system was on the same frequency that the GoGo V were using. Afterwards she wanted to join the GoGo V but couldn't because Mondo Tatsumi only designed the team for five people. So instead she occasionally aids the GoGo V in anyway she can and never got in their way.

In the finale, Kyoko reported Grandiene was still alive, after noticing her when she went up into orbit in a shuttle. Later when Mondo sent her to give the GoGoFive the information on where to find the Max Victory Robo Sigma Project, and just after she barely escaped the destruction of BayArea 55, Kyoko received the phone call from Ritsuko Tatsumi who had just come out of her coma and was able write down the call back number. Kyoko was able to pass both pieces of information on to Daimon and Matsuri which would be instrumental to the GoGo V's final victory.

In the GoGo V Movie, she briefly gained the SiegTector armor from Sieg before he died. Using the power, she became Sieg-Jeanne, transforming with the call of "Sieg, Transform!", armed with the SiegBlaster. By transferring all the Demon Hunter powers to Victory Robo, she helped the GoGo V destroy Golomois.

Analyse Robo Mint
Cheery and child-like analysis Robot who controls the GoLiner at the Ba yArea 55 base.
Big Douser
It was designed by Nagare and dispatched by the Chemical Firefighter Brigade, it was designed to extinguish fires but was possessed by Saiman and had to be destroyed.
Mizuki Kido
Mizuki Kido, Matsuri's dear friend, who had been injured and looked to be crippled, showed up in Episode 9. An accident with the monster of the week transferred Matsuri's powers to her, and she had to fight as one of the Gogofive, until she was successful in returning her friend's powers. The episode reawoke her own courage, and she went at her rehabilitative therapy with a new gusto.
Jiku / Demon Hunter Sieg
Appeared only in GoGo Five: The Movie, Juki was last of a people who had fought and defeated the Juuma, who were mostly exterminated by Golmois. Only Sieg survived and wanted revenge. He pursued Golomis to Earth and encountered the GoGoV, whom he blamed for saving the people in the crossfire instead of fighting Golmois. It took Kyoko, who reminded him of his superior officer Riria, to remember what he was fighting for. He wielded the SiegShot, SiegSword and SiegBlaster. When he was killed by Golomois, he gave Kyoko the gem that held the Demon Hunter powers in it. Transformed with his jewel by shouting "Sieg, Transform!"
Teamed up with the GoGo Five to battle King Gill and the Dark Beast in 'Gogov vs Ginagaman'.
A year later, the GoGo Five teamed up with the Timeranger in order to defeat a newly returned Pierre and Londarz prisoners enhanced by his Saima Magic in 'Timeranger vs GoGoV'.