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