>>29797171QR's get added to seen pokedex they don't let you find them outright. National dex can show up if you're lucky, some dude got a Chikorita yesterday but couldn't post QR since no national dex and obviously OP found Oshawott
Scan 10 QR codes (2 hour cooldown per scan and 10 can stack at once)
Then use island scan and a rare pokemon will show up for 1 hour on the island
Have the whole island explored and all the ride pokemon since they can show up anywhere on the island