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