Charon.
There is no planet that has the same size moon as the planet. This is only possible if Pluto was still a planet.
It is a moon of the dwarf planet Pluto. They are so nearly the same size it could almost be called a double planet system
Mercury is roughly the same size, but it is bigger than our Moon.
Earth.
Neptune; it is almost as large.
Pluto
Pluto would be the best answer, but Pluto is only a dwarf planet. Also its largest moon, Charon, is still not as big as Pluto itself.
Neptune is almost the same size as Uranus. Both planets are similar in diameter, mass, and composition.
Venus because it is almost the same size as Earth.
A planet the same size as Pluto would likely be classified as a dwarf planet, given the criteria set by the International Astronomical Union. It would have a diameter of about 2,377 kilometers and an orbital path beyond Neptune in the Kuiper Belt.
Pluto has a moon named Charon that is about half the size of Pluto itself, making it the largest moon relative to its planet in the solar system. This close size relationship is unique among dwarf planets.
the planet you are looking for is Pluto it is about the same size as its moon and now scietist no longer call it a planet