Prestiging against Chansey

Due largely to the Valentine's Day event, I was able to test my theory that Wigglytuff is an effective counter to Chansey for prestiging purposes. I had previously used a CP 1500 Wigglytuff with P/HB to absolutely demolish a CP 1000 Chansey that was at the bottom of a friendly gym otherwise filled with much higher CP pokemon.

Since the V-day event began, I've accumulated a small army of Wigglytuffs in the CP 700 to CP 1200 range, keeping only the ones with P/HB or P/PR. They are fine generalists attackers, but my main purpose was to have attackers that can handle a Chansey of slightly higher CP (thus giving me at least 500 prestige for a win against Chansey). Last night, I encountered a level 2 enemy gym with only a single Chansey (CP 1017) defending. I put a CP 961 Wigglytuff (P/HB) as my first attacker. The battle was long, but the Wiggly took down the Chansey with about 10 seconds remaining. I was only dodging charge moves (hyper beam, in this case).

So, it is indeed possible to beat a Chansey with a mon of lower CP, and Wigglytuff is up to the job. I don't think it is possible to defeat Chansey with an attacker with half the CP of the Chansey (thus gaining 1000 prestige), but gaining 500+ is not too bad, considering the problem Chansey poses for prestiging. Has anyone come up with any other good solutions to prestiging Chansey?

BTW, I felt kind of bad knocking out the Chansey. She looked so sad and vulnerable as she was fainting.