Nebby is a key character in Pokémon Sun, Moon, Ultra Sun, and Ultra Moon. Nebby is a Cosmog owned by Lillie and nicknamed as such, serving as one of the central figures in these games. Like all Cosmogs, it exhibits child-like behavior and often seems oblivious to its surroundings. Its curiosity and carefree nature sometimes lead it to ignore common commands. Despite this, it trusts certain individuals, including Lillie. Nebby shows a particular interest in Alola's ruins and Guardian deities, which prompts it to leave Lillie's bag on its own, unaware of potential dangers. To protect itself and others, Nebby uses its abilities to push objects away or teleport to new locations.
In the Pokémon Series Sun and Moon, Ash takes care of a Cosmog also nicknamed Nebby by Lillie. It becomes his fifty-second Pokémon overall. Eventually, Nebby evolves into Cosmoem and then into Solgaleo. In Pokémon Evolutions episode 2: The Eclipse, Nebby appears in a flashback as a Cosmog being attacked by Spearow at Mahalo Trail.
It later reappears in another flashback as a Cosmoem, used by Lusamine to open an Ultra Wormhole. Lillie then takes it to the Altar of the Moone, where it evolves into Lunala. When Necrozma emerges from an Ultra Wormhole, Nebby battles it but ends up being absorbed. As a Cosmog, Nebby features alongside Lillie and Selene in the GOTCHA! music video. (Source: Bulbapedia, edited)
