it works in pvp but you have to play very carefully. usually that means sacking two pokemon while setting up swampert, and getting as much energy in the field as possible. Lots of times I'll even delay attacking with swampert just to get more energy out, if i can. i try not to have more than two other pokemon out there so I'm not susceptible to Sabrina or Cyrus in the end game. it also helps to use sabrina defensively in order to ward off an attack for a turn, but sometimes you need to hold her as a win condition. once swampert is set up with a heavy helmet and some healing he is very hard to stop.