Where to Find and Catch Goomy
From Pokemon Go Wiki
Goomy are found and captured in Nest and Habitat locations.
Nests
Goomy Nests are locations that consistently spawn Goomy.
Habitats
Goomy Habitats are spawn locations where Goomy 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: