No Code Necessary. Just claim via Mystery Gift -> Receive via Internet. There will be 2 gifts available
Before JV asks, yes, you will need a copy of either Pokemon Sword or Shield, and a Nintendo Switch ;)
From Serebii.net
Pokémon Sword & Shield
A new Mystery Gift has started to run on Mystery Gift > Receive Via Internet.
Two gifts are available: One is a Level 15 Hidden Ability Galarian Mr. Mime and the other is a collection of balls: Lure Ball, Heavy Ball, Moon Ball and Dream Ball.
At present it's unclear why these are being distributed or for how long they'll be given but we'll provide details as we can
Cheers op! Lol at JV comment