This is a Wild Area event held by Sword and Shield. This event gives players a 2% chance to find a guaranteed Shiny Snom in 5-star raids.
This event was originally available from September 9th, to September 19th, 2022.
To import these files into your save, use PKHeX's block importing function. Our tutorial should guide you through it.
Our first post of this page contains some data relevant to the importing stage.
There's info and some common questions regarding Wild Area Events here.
To see other Wild Area Events, here.