Normally, opponent attack copying based decks are bad. There are easy ways to do it, Clefairy EVO/Mew FAC, Sudowoodo FAC (I think?) Zoroark BW/Zoroark BREAK, etc. and now of course Malamar. These fit better as techs than their own decks, since they often have many auto losses. Examples of current include Blacephalon decks, as you carry 0 Fire Energy. Pikarom’s Full Blitz also gives you no secondary effect, and while 0 for 150 is good, consider that they 1.) haven’t Benched it and 2.) will kill your Malamar next turn. Zapdos’s attack isn’t too particularly useful, since you can maybe only OHKO Jirachi with it.
Attack copiers are often too situational to build their own deck around. However, Liepard BCR copies your attacks, at the risk of a flip coin. If you would like an attack copying deck, Liepard BCR with high-energy attackers like Guzzlord-GX, Dialga-GX, Reshiram & Charizard-GX, is your best option. It is expanded, however, so keep that in mind.
Hope any of this helped!