"Rare non-legendary Pokemon"

I was inspired by this thread, which points out that glameow is a strangely rare pokemon to collect, being a version exclusive in its debut generation and then obtainable in a hidden grotto only during a funfest mission, but only in White 2, and finally during ORAS at mirage spots, which are randomly generated once a day, so still not an easy feat if you need one. This means that this line is only available in 4/17 main series games released since its debut, and I'm not sure White 2 should even count.The point of this thread being, what are some other obscure pokemon that are potentially the hardest part of completing the national dex? via /r/pokemon http://ift.tt/2DH5EUp