SO SO THIS WAS A REAL THING IN REAL LIFE! During my various course studies of Japanese history, I remember an instance where Japan (specifically Okinawa) was having trouble with a certain species of venomous snake. And so they introduced a foreign species of mongoose to help deal with the issue. Unfortunately, the mongoose didn’t help out too much and Japan wound up with a ton of mongoose, making in an invasive species.
What does this have to do with Alola and it’s real world counterpart, Hawaii? I’M GLAD YOU ASKED! Well! It turns out that SAME species of mongoose was introduced to Hawaii to deal with an outbreak of rats during a prosperous sugar cane farming season!
To further specify about this mongoose, it’s plainly called the Small Asian Mongoose ( Herpestes javanicus ) and it originally hails from South/South East Asia. It looks like this:
So this could lead to a couple of possibilities for that “certain other pokemon” in Sun and Moon. If they are to follow what happened in history in Hawaii, we might expect another rat-like Pokemon. If for some reason, they follow what happened in Japan, we could maybe expect a snake.
These are just my observations based off real-life events, so we’ll have to wait and see what the future holds for us in Pokemon!