Super Sentai Anniversary Sixth Heroes And The Power Of Three!
Shirogane/Gao Silver (25th Anniversary)
Gao Silver is the very first sixth ranger who gets a combining mecha instead of a regular non-combining mecha. This may be because Gaoranger is the start of the multi-gattai era and the may be the beginning of a new era of Super Sentai. The Gao Hunter is a combining robot composed of Gao Wolf, Gao Alligator and Gao Hammerhead. He's the very first sixth hero to have not one but three assigned mecha at once. Fair enough, the Gaorangers were getting more than one Gao Animal in their inventory so the sixth ranger ends up getting three Gao Animals when he's introduced. He can also use any Gao Animal that forms the arms of the other combinations.
Eiji Takaoka/Bouken Silver (30th Anniversary)
Another silver ranger and it's not too surprising either. Eiji's new program involves Bouken Silver to use GoGoFire, GoGoAider and GoGo Police to form his personal mecha - the Siren Builder robot. What's amazing is that Eiji seems to have references back to Shirogane considering both of them have curses to deal with. He's half human and half-Ashu. He had no idea of his half-heritage and had an ongoing rivalry with Rei and Gai who later became the Questers. Like Shirogane, he initially had fought the heroes before becoming part of the team. The mecha forming his personal robot's arms can also be interchanged with the other GoGo Vehicles that form the arms of certain combinations.
Gai Ikari/Gokai Silver (35th Anniversary)
While his mecha isn't a combiner like Eiji and Shirogane but he still has the power of three. In his dreams where he becomes the "chosen one", he's visited by three dead characters namely Naoto Takizawa, Burai and Mikoto Nakadai. Whether or not he really died in that incident where he was hit in the truck and that he came back to life isn't made clear. His power is fully activated by the Time Fire, Dragon Ranger and Abare Killer keys. His mecha the Gouzyujin has three modes: drill, dinosaur and humanoid mode. So he still counts in the power of three. Gouzujin can also combine with Gokaioh to form GoZyu Gokaioh.