Pluto

Pluto (冥王星 Meiōsei) is a dwarf planet on the Kupier belt. It was originally considered as an planet in the Solar System for 76 years. It is named after the Roman deity Pluto, the god of the Underworld, who is known in Greek mythology as Hades. The planet's symbol is ♇.

Pluto turned into "not a Solar System planet" when the IAU definition of planet changed in 2006 after the planet Eris was found. Their definition turned Pluto into a dwarf planet.

As portrayed in Pretty Cure of the Stars
In Pretty Cure of the Stars, Pluto is the home base of Team Freddy, consisting of Freddy, Big Man, Hula, and Sky. Team Freddy wants to take over the whole solar system, and also Pluto, Pallas, Ceres, Juno, and Vesta, ignoring all of the others that don't belong.