Solgaleo and Lunala were introduced as the mascots in the Generation VII games, Pokémon Sun and Moon. Solgaleo is an emissary of the sun known as the "beast that devours the sun". Lunala is an emissary of the moon known as the "beast that calls the moon". According to Pokédex entries, Solgaleo and Lunala are said to be, respectively, the male and female evolutions of Cosmog. However, the gender of both are actually considered unknown by the games.
Similar movesets
Solgaleo's signature move is Sunsteel Strike, a damage-dealing Steel-type move that ignores the target's ability. Lunala's signature move is Moongeist Beam, a damage-dealing Ghost-type move that ignores the target's ability. For the duration of these moves or when using their special powers during the games' storyline, Solgaleo and Lunala change into their Radiant Sun phase and Full Moon phase, respectively.
Spoiler warning: this article may contain major plot or ending details.
In Pokémon Sun and Moon, Lillie takes care of a Cosmog named Nebby, which she fled from Aether Paradise with in order to save it from the Aether Foundation's experiments. Lillie keeps Nebby in a bag as an attempt to both keep it safe and to keep it from sight. Lillie and Nebby are eventually kidnapped by the Aether Foundation, and Lusamine takes Nebby and uses it to open Ultra Wormholes. Nebby then evolves into Cosmoem. Later, when the player and Lillie play the Sun and Moon Flutes at Altar of the SunneS/Altar of the MooneM, Nebby evolves into SolgaleoS or LunalaM, which is then caught by the player.
Spoilers end here.
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