theSLAYER

When you select Scan QR Code from your in-game menu, you can register Pokémon as Seen in your Pokédex.
Players can go to their registered Pokédex Entries, to share QR codes for other players to scan.

However, for certain Pokémon, when you try to generate a code in-game, it'll give the "This is a special Pokémon. There is no QR Code." message (as seen below).

This album hold such entries. Their QR codes were scanned from Japanese Ga-olé disks, which was marketed as being able to be scanned into SM and USUM. However, these QR codes are region locked to JP consoles only.
 

When you select  Scan QR Code  from your in-game menu, you can register Pokémon as  Seen  in your Pokédex.
Players can go to their registered Pokédex Entries, to share QR codes for other players to scan.

These codes were generated so that players can have them  Seen  in their Pokédex.
Can be useful for finding their habitats in the dex, or having them show up in  GTS  search function without having to type it's name.
note: if the image says “JP 3DS only”, you’ll need a Japanese 3DS. Additionally, as these entries are not in the Alolan Dex, they’ll be marked as seen (despite not being visible in the Dex) and can be searched on GTS (their name appears under the alphabetical search, meaning users won’t have to type in their names). No other function.