If basic metals and dark had the regular effect, it would be too broken. Most people would now use pure Dark or pure Metal decks. Not to mention Some people would be using Swift attackers.
it's just not good enough. u dont really have a searcher/drawer in the deck, and gardy's atk depends too much on damage counters and bench pokemon, the 2 things u cant really control.
If basic metals and dark had the regular effect, it would be too broken. Most people would now use pure Dark or pure Metal decks. Not to mention Some people would be using Swift attackers.