Swarmed by what? Yanmega? As long as he drops 2 Oddish and 2 solosis at a time, Yanmega can't take them out. Once the stage 2's are in play, there is nothing you can do really. And, his energy attachments all go to attackers with never worry of getting gusted or worries of being KO'ed with their high HP and Reuniclus. The only other threats of an attacker right now are Zekrom, which can't KO Ross's dragon's, and Magnezone, which Pablo already covered, it can't continually set up and LZ enough energy to win.
I'm guessing...$2. It might see a jump in popularity, but there is a trainer in the next set that does the same thing. Granted, it can't be run with Vileplume, but not everyone is going to run this deck.