It's funny. Everyone is trigger happy with the "ban" weapon.
I mean seriously. If the good, BAN IT!
If it is part of a deck that happens to be really good, BAN IT!
If people don't like it a little, BAN IT!
Stuff doesn't need to be banned as much as countered against to make match ups better.
*cough* night March *cough*
Exaggerations are probably not helpful for this topic.
Pokémon rarely bans
anything. Are there some players that want to ban a lot of cards, often with poor justification? Absolutely, but they aren't "everyone". Even in this thread, many are giving sound reasons for it. Being countered does
not make a card balanced. It can, but it is not guaranteed. There is also the skill threshold; if something is causing a problem at all skill levels but the top, that isn't a success for the design team either since they aren't targeting this TCG to such a narrow audience.
Getting more general (as in this isn't just something I'm telling Phoenix15), there are some cards that you can tell are going to cause issues just through a basic understanding of the game's fundamentals.
Double Colorless Energy ought not to ever have been reprinted for Standard play. It was however, and the answer was obvious: allow it to rotate out. The games designers did not, even though it was quite clear that the intended combos were working out a little too well, and that is discussing the metagame from the HS-era sets. While it helped make some cards viable for competitive play, in doing so it crowded out others. When it was reprinted for the BW-era, we saw it continue to do likewise and then some as we started getting Pokémon-EX that - though not all thanks to
Double Colorless Energy - were able to hit too hard, too quickly to allow enough time for other game mechanics which were intentionally designed to be slower and dictate the pace of the game to function properly.
Double Colorless Energy is not the only card that I believe causes problems, but it is the easiest one to pinpoint and where the ramifications seem the easiest to estimate. As this discussion was about the
one card to ban, I believe this is it. The answer to improving the game is, however, not that easy: instead of banning (short term solution) the powers-that-be need to dial back the pace of the game which involves overall card design.