It appears that this gift was distributed to players via a serial code, to promote players to visit their local game shops prior to the release of DLC 1: Isle of Armor.
The event was distributed to a few regions:
Europe - from June 05 to July 05, 2021.
Ireland - from June 29 to July 31, 2021.
US - from August 14 to August 31, 2021.
Using the Dynamax Crystal would allow the Pokémon to appear at the Watchtower Lair's Den as a max raid.
To be able to use the items associated with the event, including injecting items into the save and getting it to work,
the player's Switch must be connected to the internet, with the Mystery Gift>Get Wild Area News option used during the event period.
Alternatively the player must have connected to the internet and redeemed a Mystery Gift during the event period.
This gift can be redeemed on either Sword or Shield.
As of time of writing, this event is the only way to get Curse on a Copperajah that can Gigantamax without breeding move transfers, from event raids. This events also has a certain fixed IVs.
As of time of writing, end date for the serial code redemption is presently unknown.
In order for the item (whether redeemed or hacked in) to function, players would need to have at least Wild Area Event #18 downloaded into the save.
(When collecting a Mystery Gift, a copy of the Wild Area News would be downloaded to the save)
As of LGPE, wonder cards are no longer stored in saves. As such, players will not be able to inject this event into their save using PKHeX.
Format Ver.2.0.0-10, Post Updated Date:20200606_1536
Original News Post: