Many people I know who play the Pokemon TCG and many people I read about here at the pojo are constantly changing their decks because someone built a deck to counter their deck ideas. My tip is DONT USE A SINGLE DECK IDEA. So many decks are based on a single thing like speed, screwing up your opponet, screwing your opponents pokemon and so on. Some decks I have seen use Ditto and Clefable to copy opponets attacks, or Slowking fossil Psyduck and Chaos Gym to mess with trainers, or just use ER's SER's and energy removing attacks. Mixing up the ideas is best. One the best deck I've ever used used Blaine Charmander's Kindle attack, Ditto, and Slowking or other disruptive cards. If my opponent would use an ecogym, I would use ditto to hit them back. If they brought out a heavey hitter to take out ditto, I would destroy all of their energies with Kindle. When they used trainers to get more energies, Slowking foiled their plans.if they built a deck with low attack costs to make Kindle useless, all i had to do was use ditto. If they built a deck to make dittos power useless, Kindle did the job. If they built a deck to destroy my whole deck, they lost to everyone else so they changed their deck again. I've been using this Idea for quite some time now and I've hardly ever changed my decks.