>>29827386in your ingame pokedex you can press the qr button to generate a qr code for the pokemon you've selected. you could make a photo of your display and then scan that photo to scan your own dex entries this way (or just use any of the qr code lists that already exist)
>>29827397probably not, being registered in the dex doesn't mean it pops up, the qr codes just mark the pokemon as "seen" in your dex, the island scan is not influenced by the type of qr code you scan.
>>29827403I think you unlock qr code scanning in the first city or something, that's when you can start to scan. When you do the island scan you need to be able to get to the place where the pokemon spawns though, which might not be possible early on (e.g. getting to horsea without surfer). But you can just save beforehand.
