This gift was distributed as part of the Pokémon Adventure 25 (Grab these Mythicals) campaign.
The gift codes can be obtained via exchanging scraps for codes.
User could exchange their scraps on this site: http://adventure25pokemonkorea.co.kr/
Do note this site limits access to Korean IP only.
Format Ver.2.1.0-2b, Post Updated Date:20210426_1630