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