At 165 Galaxagos has the highest Special Defense of all Pokémon in the Sage Pokédex.
At 29, Galaxagos is the slowest fully evolved Pokémon in the Sage Pokédex.
Galaxagos is based on a sea turtle. Its shell resembles the lunar surface, and it has small meteorites which orbit it.
Galaxagos may be a reference to myths about a World Turtle, or to Great A'Tuin from the Discworld series (which is itself a reference to World Turtle myths). The fact that its offspring orbit it like planets is especially reminiscent of a sub-plot in the Discworld novel The Light Fantastic.
Galaxagos's name is a combination of galaxy and Galápagos.