You can get everything that isn't a mythical, a ledgendary or an Ultra beast barring the exception of Phione, Type null and Piopole*
I generally prefer items over as I have everything breed out and everything I want trained already more or less trained
Not 100% sure where you can evolve Cubone for the Alolian variant but am pretty sure it's in the dessert which is late game
I have these spare