coming back to this: transferred over a Unovan exeggcute. It evolved into Alola ExeggutorI don't think so. I'm pretty sure these Pokemon will evolve based on the region they were caught in, and in addition we already know that non-Alolan form Pokemon will pass down their regional form preference during breeding with an Everstone. The alternative is that it is impossible to breed for a non-alolan Exeggutor in Sun/Moon and that the only way to get non-Alolan Exeggutor in Sun/Moon is by transfer.
i dont have any of the gen 1 VC games to see if the GB tag protects them but surprise! they went with the dumbest possible way to handle this