Yeah. Back in the day, there was only 150 documented species of Pokemon. With Togepi, it shot up to 151, and then the Johto Region added another bunch of Pokemon. And then the Hoenn Region added to the dex and then the Sinnoh Dex. And then the Unova Dex had its own fair share of Pokemon that weren't even in any other regions. Kalos had its own stuff too, but a good amount of Pokemon found in other regions, and Alola just seems to have all sorts of things like Regional Variants.