A Shiny Amoonguss was distributed as part of the promotion for the Pokémon Sword and Shield Trainer's Cup YouTube stream broadcast by Pokémon Korea. The Amoonguss is based off of the one used by World Champion Senior Top 4 player Baik Jongyoon in the 2019 World Championships.

Shiny Amoonguss Details:

Level: 50
Moves: Clear Smog, Spore, Protect and Rage Powder
Gift Period: August 9th, 2020 until August 10th, 2020 at 23:00 pm
Serial Code: TRA1NERSCUP

Sources: https://www.facebook.com/PokemonCoKr/posts/3266479700058042 and https://pokemonkorea.co.kr/ptc2020