There are a LOT of super uncommon or rare pokemon in the starting area. Things I've found will be below, mind the spoilers.
Ralts, Chewtle, and Happiny are all things I've only seen ONE of... and I'm sure there's more. I've also only seen a couple of Sunkern. But I've caught probably 15 different species in just the opening area, so... lots of nifty stuff to be had.
