Go to the location within the next hour and attempt to catch it, though note you have just this single battle to do so. Island Scan will reveal a non-Alolan Pokémon on your current island for you to catch (the full details of which are at the end of this article). For every scan, you earn 10 points, and every 100 points allows you to use the Island Scan feature. You can only use the QR scanner 10 times a day. It'll then be added to your Alolan Pokédex, revealing where you can catch it in the game.
The camera will activate, and place the desired QR code in front of it and snap. To scan a QR code, open the menu, head to the second page and select the 'QR Scanner' option. How QR codes and Island Scan works in Pokémon Sun and Moon There are a few caveats to the system - and it will take you some time to scan then all - but it's well worth doing if you want to, ahem, 'Catch 'Em All'. Not only is it a useful way of cataloguing creatures so you can later locate them in the wild, the system also allows you to catch an additional 28 non-Alolan Pokémon that you can't get anywhere else - until Pokémon Bank support from previous generations is introduced, that is. Pokémon Sun and Moon QR codes allow you to scan codes of (practically) every Alolan Pokémon and add them to your regional Alolan Pokédex.