I'm not very good at TCG, competetively anyways and I don't really play at all. I'd still have to agree though that because there are such things as strengths and weaknesses, you can't define the best Pokemon card. I have a feeling the Arceus line will be good. The Arceus rule and Arceus X attack, Creation, seem to me like if you can get a hold of several Arceus cards with the appropiate amount of energies, would work well in a deck especially because the they coordinate with eachother.
Anyways, value-wise, there is a best-Pokemon card (which is the way I collect.) One priceless card is Trophy Kangaskhan worth over 800 dollars. I think there are some japanese Pokemon cards that are out of this world, in the thousands range. In those means, there is a best Pokemon card. =)
- Luigi