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