For me I live in Boise Idaho. So the area is technically a desert, but we have a lot of green, and also barren desserts. So I'm stumped, I doubt there would be real hardcore desert Pokemon. But some might. We have coyotes so possibly some mightyena. We have birds and pets. We also have gophers so as I said before I'm not sure what I'd have. It'd be cool to know though.
What, another inhabitant of potato-land? I could have sworn I'm the only one out here...
Anyways, to add to that. My brother and I had this discussion something like a week ago, and we both agreed that Idaho would probably have Vulpix/Ninetales/Fenniken and evos (foxes), Teddiursa/Ursaring (bears), Mightyena/Absol (closest I can think of to wolves), Various normal/flying birds, Murkrow/Honchkrow, (crow) the common pets in Purrloin, Meowth, Lilipup, and Growlithe, Deerling/Sawsbuck (deer), Joltik/Galvantula/Spinarak/Ariados (spiders), Ponyta/Rapidash (horses), Miltank/Tauros/Mareep/Flaaffy/Spoink/Grumpig/Tepig and evos/Torchic and evos (farm animals), Patrat/Watchog (gophers/groundhogs), Rattata/Raticate (mice), Rufflet/Braviary (eagles), Stunky/Skuntank (skunks), Buneary/Lopunny (rabbits), Zigzagoon/Linoone (raccoons), Zubat/Golbad/Crobat/Woobat/Swoobat (bats), Cyndaquil/Quilava/Typhlosion (if you count them as mice, weasels, and/or badgers.) Onix, Geodude, Skarmory and other rock/steel types in the more rugged terrain and the mountains, various desert dwelling pokemon such as Trapinch and Cacnea near the sand dunes, fire pokemon towards the more volcanic areas up north, and don't even get me started on fish...
I'm pretty sure we came up with even more, but I can't remember them off the top of my head. Pretty diverse though.
For starters, I can see the Kanto trio working well, as all 3 species are probably present here. (if you count Bulbasaur as a more toad-like creature)
Legendaries, I can't be sure, but I could see something that would dwell in the mountains? Regirock, Registeel, or Heatran maybe. And Rayquaza tends to fly around, so maybe he'd show up every now and again. Guess that argument could be made for anywhere though.