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