Vulpix's automatic sun enables chlorophyll sweepers to become unreasonably threatening, well beyond the caliber of other offensive cores, with minimal effort. Bellsprout in particular has no reliable counterplay whatsoever - it can't be reliably switched into unlike other sweepers, and it can't be traditionally revenge-killed unlike other wall-breakers - but other Chlorophyll sweepers also require more specific checks in the builder, and more careful play in the game, than other offensive threats do.

The issue is automatic sun because manual sun is an entirely different archetype that should be separately evaluated. The opportunity cost of using poor heat rock mons and, more importantly, the difficulty of having to both get the manual setter into play and find the chance to use Sunny Day, is an offset to the presence of the sweepers when setup does succeed that autosun doesn't have.