F.A.Q.
Q) Is this legit?
A) Legit means no external tools, hacking and/or glitch abusing are used. At best, Pokémon obtained in this way can be legal. Do note that trading Pokémon obtained this way without proper disclosure might be considered scam.
Q) Can I follow this tutorial with a clean, non-hacked Switch unit?
A) No, Atmosphere CFW is required.
Q) Can I follow this tutorial while being offline or with my EmuNand/Emulator?
A) No, this requires you to be online and connected to Nintendo official servers.
Q) Can I follow this tutorial without an NSO (Nintendo Switch Online) paid subscription?
A) Yes, Mystery Gift features don't require NSO.
Q) Do I risk a ban by using faked BCATs?
A) Who knows. As of now we don't have any ban reports but, as always, we don't take any responsability in case your console, game or savefile gets banned. The method is similar to save file backup / restoration, and as of now we don't have ban reports for that either. If anyhow you're too worried to proceed, just avoid following this tutorial.
Q) Why can't I add more than one (1) wondercard per time to Let's Go Pikachu/Eevee BCAT?
A) The game would only see the first card on the BCAT list. There would be no point in allowing users to add more cards.
Q) Why does the tool flags some of my wondercards with a yellow warning mark or with a red esclamation mark?
A) The tool marks wondercards as invalid in these cases:
Q) Can I edit the wonder records receiving date?
A) Technically, yes. Suggested? No. There have been ban reports for tempering with the Internal/Network Time Clock.
Q) Can I edit the Met Date for received Pokémon in Pokémon Legends Arceus and Pokémon Scarlet/Violet?
A) Same answer as point 8.
.....