From Bulbanews, your community Pokémon newspaper.
To be available June 17
Codes for Pokémon based on Mallow's Steenee, Kiawe's Turtonator, and Lillie's Alolan Vulpix will be distributed at Æon stores in Japan starting June 17, 2017. These codes can be redeemed in Pokémon Sun and Moon.
Codes for Mallow's Steenee will be available from June 17 to 25, 2017; codes for Kiawe's Turtonator will be available from June 26 to July 4, 2017; and codes for Lillie's Alolan Vulpix (nicknamed Snowy) will be available from July 5 to 14, 2017.
To obtain the code, players need to either purchase a Pokémon Sun or Moon game at the Æon store, or show the title screen of their Pokémon Sun or Moon game.