I'm assuming that you're asking about the TCG? If that's the case, then any sets after Black & White Next Destinies aren't able to be used in official league play under the Modified Format. You can still collect the older cards and play with them recreationally, though.
Since I'm not an expert on the card game though, I'll move your thread over to our Pokemon TCG forum, in case you have any more questions or you'd like someone to elaborate a bit further.
MOVED.