I downloaded the new update. I've got foreign Pokémon into the game. But the National Dex seems to be missing. I went to talk to the professor. No dice.
There is a national dex in Pokemon Bank. Check this site.
There is only the alola-dex. As far as I know, there is no national-dex in Gen 7.
Sorry, but currently you cannot get the national dex in Pokemon sun and moon. :(