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