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