When Alola was opened to sailors around the world, Meowth arrived in the region as stowaways. And when their ships left the docks of Hau'oli or Heahea City to return home, the unwitting sailors brought new pokemon with them – the tiny Grubbin, drawn on board by the electricity of the ship's Lanturn.
In Alola, Grubbin have long been viewed at best as an unfortunate but necessary phase of a Vikavolt's lifecycle – at worst as pests who drain the sap from precious trees and shrink the harvests of their berries. But humans have found value in many species of tree, some of which were not nearly as harmed by the depletion of their sap. In many parts of the world, the Grubbin found nothing to eat and simply starved – but in the vast forests north of Unova, where many expected these tropical pokemon to freeze, they became the beloved companions of maple syrup makers in search of trees to harvest.
A Grubbin's sense of smell is finely tuned to the sap of mature trees, and its mandibles are perfectly shaped for making incisions without undermining the tree's structure; they are parasites, not predators. The holes they cut, unlike those bored by Pikipek, are low enough to the ground for humans to reach with a bit of crouching – and their small size and large mandibles leave the sap flowing long after they finish. And wherever maple trees grow, humans have learned to follow the Grubbin to refine and bottle the sap they don't devour.
Curiously, some Alolan legends speak of Grubbin leading people to berry trees in the same way – back in ancient times, when fewer humans lived in Alola, before farms and orchards replaced wild forests. The Grubbin, for their part, are happy to be beloved in a different land.