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