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