Where to Find and Catch Gourgeist
From Pokemon Go Wiki
Gourgeist are found and captured in Nest and Habitat locations.
Nests
Gourgeist Nests are locations that consistently spawn Gourgeist.
Habitats
Gourgeist Habitats are spawn locations where Gourgeist is likely to be encountered, but not guaranteed the way a Nest is.
Additional Tips and Information
Best Nests
If you know a really good nest or any of the nests above is really good, list them here: