That being said, for a long time I was against Pokemon. But DS loves them. His friends love them. The cards have helped him learn to read, and develop social skills like bargaining and trading and sharing.
I still dislike Pokemon cards. I think they're dumb. But you know what? When I play with the cards with DS, he is so happy I have my own deck, even.
He doesn't play with them a lot, and for him they are more of a social currency than anything else. So I let it go. I wish I could have found a way to not let him have them and still feel included when his friends play with them, but I couldn't.
I'm not saying to let it go. I'm just sharing my experience. I wish you good luck!
Also, I'm sorry some of the replies that you are getting aren't very kind or respectful. I want you to know that I support you completely. If we don't raise these kinds of issues, consumerism directed towards our children will never change