Momo Maruo
In Gokaiger episode 31, Momo, former OhPink, works for UAOH alongside and offered to freely give the Greater Power of the team to the Gokaiger after making them do things to butter her up so she could create a diversion for Gorou. However, the Gokaiger refuse the power, rather choosing to earn it than merely be given the power.
Goro Hoshino
Former OhRed Gorou returns in episode 31 of Gokaiger, he attempts making a transaction with Basco for their Greater Power for information on the location of the Gigant Horse Flagship. Goro wanted to take back the stolen Greater Powers (Maskman, Changeman and Flashman) to which he failed in. The Gokaigers came to save him and defeat Basco but are soon overwhelmed by Basco's true form. Gorou and Momo rushing to their aid and gave them a hint to the Ohranger power leading to the GokaiGalleon Buster.
Ryou (Ryuuranger of Dairanger) appeared in Gokaiger Goseiger Super Sentai 199 Hero Great Battle, approving his Greater Power to the Gokaiger and returns again in Episode 33 to help Gai get off his feet after having his arm injured by Basco.
Sosuke Esumi
Sosuke Esumi nicknamed the "Speed King," is happy go-lucky car racer who became Go-on Red to aid his Engine partner Speedor in the fight against the Gaiark. He hitches a ride with the Gokaigers to Gunman World, only to be barred from getting back to Human World by Babatcheed. The Gokaigers, Sosuke, and the the Engines then decide to go to Machine World to convince Machalcon to help them. He is now a legitimate race car driver.
Speedor, Bus-on, and Bearrv are Go-on Red, Blue, and Yellow's respective Engine partners and denizens of Machine World. They battled Chirakashizky in Gunman World, only to have their power taken away and shrunk down to their Engine Cast size. They are reunited with Sosuke, and Speedor and Bearrv reveal that they got married and had a child, Machalcon, who they never see much of since they are battling evil.
Bomper is a pink radar robot created by Jum-bowhale from the Machine World, who supported the Go-ongers by creating their arsenal and performing maintenance on the Engines. He lands on the Gokai Galleon asking for the Gokaigers assistanc e and eventually reunites with Sosuke.
Kenta Date was originally a slacker at Moroboshi High School who was chosen to become the Megarangers' Mega Red and battled the forces of Nejirejia. Kenta became a teacher at Moroboshi High prior to him battling in the Legend War with his team. Meeting the Gokaigers, Kenta offers to give them his team's greater power if they become students for a day. He is lured into the woods by Sally and is threatened by Basco with bombs placed all over the school. Gai intervenes until the other Gokaigers took care of the bombs. He gives his team's greater power at the end as promised.
Domon was formerly a professional grappler who became Time Yellow of the Timerangers from the year 3000 to capture Don Dolnero and the Londers prisoners. In the process, he and the others altered events in the present. Once stopping Gien from destroying the present, Domon returns to his time unaware that his girlfriend Honami Moriyama, whom he reveal his true identity to, bore him a child. But when he sends the Gokaigers to October 2, 2010, to avert the destruction of a shrine by the Matrintis Empire, Domon learns of his son's existence by chance when Gai sends him a picture of Honami and their child Mirai.
Honami Moriyama is a reporter and photographer, not only daring enough to take photographs of the Londers Family but is also uncover the Timerangers' true identities before deciding to back off. Eventually, Honami fell in love with Domon as the two begin dating. However, after Domon is forced to return to his time once the present was saved, Honami is revealed to bore him a son, who in Timeranger was said to named 'Domon Jr.' Mirai had run away, upset that his mother moved a lot and never got to make solid friends. Gai helps him realize meeting new friends is good.
He is a pupil of the 3 Shinshou who was sealed away after being fooled by Daimaou into attacking people centuries ago. He was released to assist the Kakurangers against the Youkai. His attempt to save a girl from rampaging zoo animals, caused massive property damage, forced the Shinshou to seal him at the Negakure Shrine so he could mulled over his action a decade. As a result, Ninjaman wasn't in the Legend War and was later freed by the Gokaiger. He refuses to give them the Greater Power until he tests them to see if they are worthy of it. After Gai and Doc released Action Commander Juju's spell by themselves, he is revealed to be himself. He aids them in his giant form in defeating Juju. Afterwards, he bids the Gokaigers farewell before vowing to help them in the future.

Past Sentai 1-14 |18-30
|31-45 |45-51 |199 Heroes