Scholars have acknowledged the similarity between Alola's Totem Pokemon and Paldea's Titan Pokemon from the first era of contact between the two regions, but this was invariably chalked up to convergent evolution. The recent discovery of a giant Arboliva guarding a great forest, however, did much to challenge that perception.
Dolliv are natural travelers who are known to raft long distances, even overseas, and it is difficult not to perceive a connection between Alola's guardian deities and Arboliva's signature technique, for both act upon the same altered forms of terrain; the latter exploits what the former creates. If Arboliva was indeed the original Titan Pokemon (although some academics, citing its lack of Herba Mystica, question if it is one at all) then perhaps it shared its powers and gigantism, gifts from Alola's protectors, with others, so that it could keep Paldea as safe and secure as that distant island chain.
Yet the world is a vast place, and it is not entirely obvious why Paldea requires enormous protectors, while Kalos, for instance, does not. Only a warm climate links Alola and Paldea, and one must note that Arboliva cope poorly with the cold. It gives science cause to wonder if equally enormous pokemon dot the rest of the subtropical zone, awaiting explorers to discover them. Few, however, are willing to tempt the wrath of guardian deities or pokemon the size of trees, even if it was wise to do so. For speculation abounds that the health of these habitats is quite literally linked to the pokemon that protect them, and that the sickness or removal of Arboliva and its compatriots would leave behind only a desolate wasteland.