>>30068269scan 1, it gives you pokedex data for that pokemon
scan 10, a random wild pokemon from pic related will be somewhere on your map, and you can go catch it
i've heard if you faint it, a new one will spawn. but if you catch it, definitely that will end it. so if you want a certain nature or gender, you might want to soft reset.
you only have an hour to find said pokemon, and it can spawn somewhere you havent been yet, so be careful. might want to do it on an island you have completely explored.