Quoted By:
>Exeggutor
This is common knowledge by now, but according to the Hoenn Dex entry, Exeggutor originate from a tropical region, and not Kanto. And before you suggest that the entry was referring to Hoenn itself, Exeggutor can not actually be found anywhere in any Hoenn game. Coupled with the fact that official artwork exists of long-necked Exeggutor in a tropical environment, it seems widely accepted by the community that Game Freak envisions the Alolan form as the original version, with the Kanto form adapting to the lack of sunlight and prominence of poison types in the region.
>Cubone and Mandibuzz.
Cubone is fun to talk about. Recent Dex entries have described Cubone as being the natural target of Vullaby and Mandibuzz, even going as far to suggest that Mandibuzz nests are made up almost entirely of Cubone bones. Of course, the only region where this can even really happen is Alola, meaning Mandibuzz are likely native there. I mean it makes sense if you think about it. 2/4 Islands have the Mandibuzz line flying around. Cubone live around Wela Volcano, which (along with the scavenging Vullaby) explains how Cubone can find and wear skulls that are so cleanly picked of flesh.
Some bonus points to this "theory" (is it even a theory if we're just taking canon information at such face value?) include dex entries that suggest that Cubone evolve and developed their signature bone-throwing abilities to be able to hit Mandibuzz in the sky, to avenge their mother, which is also the only explanation for Cubone's dead mothers beyond the human-caused homicide explanation from Gen 1. Obviously, Cubone in the wild can't all have had their mothers poached by Team Rocket, so here is our explanation, that their natural predators are Mandibuzz, as seen in Alola. Like Exeggutor, this could indicate that the Alolan form may in fact be the original (and depending on how Let's Go handles it, the Lavender Town Marowak may be retconned to be Alolan too.)
That's enough autism for now.