There are many different ways to unlock the other countries in “Pokemon Sun” and “Pokemon Moon.” After winning in North America, some people think that you have to defeat all of the Elite Four again. This is not true. You can also do a few other things such as trading or using passwords.
If you want to trade with someone, you need their player ID number. To get this, open up your Trainer Card and press X on the bottom screen. Then select Mystery Gift > Receive Gift > Get Via Internet. Now enter the player’s ID number and select Yes when it asks if you want to connect to the internet.
The person who you are trading with will also need your game’s serial code which is located on either the back of your game case or below where your cartridge goes into your Nintendo 3DS console itself . Once they have that, they can go into Mystery Gift > Receive Gifts > Get Via Wireless Connection and input it there instead..
If passwords are more your thing, then head over to Pokemon website here: http://www2.pokemon-sunmoon-gamecard-us/en_US/pokemonpasswords/?lang=en_US . Here you can find out what password unlocks what region!