Prior to Mohn being sucked by Ultra Wormhole, but survived, he found it at the Alola antique shop, still in inactive state. Thinking it was made by scientists to protect a princess of a far-away land, Mohn thought of his little princess, baby Lillie, and took Magearna with him, but was unable to activate it. Still, he took notes of Magearna, and drew pictures of how it could play with Lillie.
In present day after Mohn is missing, his wife Lusamine begin to show her kids Lillie and Gladion his old room, where Magearna and his old Z-Ring are, with Lillie being entrusted to own his room and sets out to activate Magearna until he's found.
Magearna is seen still inactive in Lillie's closet. Lillie was getting herself ready for school and she told it that she will see it later.
Before Magearna recently awakened, it was introduced by Lillie to her friends.
None of Magearna's moves are known.
- Magearna is one of the three Mythical Pokémon whose with the main characters, the first being a Shaymin, who Mallow is watching over and Ash's Melmetal, a fully owned Mythical Pokémon.