Quoted from PK, who I asked the same thing.
Originally Posted by Fat PK Gaming
CS Snover is more useful on offensive hail teams as opposed to balanced and stall hail teams. Its an option for users who want Snovers with barely decent speed(outspeeds neutral 95s and positive 80s) that can throw out base 180 Blizzards. I've had matches where a Snover cleaned up with blizzard after the opposing team was weakened from my Glaceon, my jynx etc.
The set isn't "great" but its an option for users who want something different imo. Just my 2 cents on it.