I've played Pokemon back since the beggining until the release of neo-genesis and back then the metal energy was a special energy card. So, I'm willing to "restart" in pokémon TCG, but noticed that now we have some kind of basic metal energy card, as well a basic dark energy card. Does the old special energy still have effects in today metagame? Or are they banned? How many cards can I have for each one? Can I still use 4 special metal/dark energy?
This has been sufficiently answered in the comments, so for the sake of getting this off the unanswered list, no. Those cards are too old for competitive use.
They are okay for unofficial matches with friends, though :)