Catch all the pokémon in the Alola Pokédex (see the List of Pokémon Locations), then go into the building to the left of the Dimensional Research Lab, go up to 2F, and go into the GAME FREAK office and talk to the game director to get a Shiny Charm. Just by having the Shiny Charm in your inventory, you will be more likely to encounter shiny pokémon.
The Shiny Charm increases Shiny Encounter rate!
Catch all the pokémon in the Alola Pokédex (see the List of Pokémon Locations), then go into the building to the left of the Dimensional Research Lab, go up to 2F, and go into the GAME FREAK office and talk to the game director to get a Shiny Charm. Just by having the Shiny Charm in your inventory, you will be more likely to encounter shiny pokémon.