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