This Pokémon was distributed to commemorate the release of the TCG Expansion: Cosmic Eclipse.
For players in Europe, players can obtain the serial code from participating retailers between October 1 to November 15, 2019.
This marks the first time Shiny Solgaleo is available in the games, as Solgaleo is shiny-locked in Pokémon Sun and Pokémon Ultra Sun.
Our news thread relating to this distribution: https://projectpokemon.org/home/forums/topic/54719-sm-usum-eclipse-shiny-solgaleo-lunala-gift/
Format Ver.1.0.8-2, Post Updated Date:20191001_0832