The secret to any great deck, both for beginners and veterans, is choosing cards that compliment each other from the same engines
They don't even need to know that they've been chosen
This includes countering them
Heres a short list of all the important cards featured in each set: HGSS: Cleffa, Tyrogue, Jumpluff, Ninetales, Pichu, Pokmon Collector, Pokmon Communication, Professor Oaks New Theory, Copycat, Rainbow Energy, Double Colorless Energy, Donphan Prime, Typhlosion Prime, Blissey Prime UL: Rare Candy, Jirachi, Suicune/Entei Legend, Shaymin, Kingdra Prime, Tyranitar Prime, Lanturn Prime, Judge UD: Sages Training, Vileplume, Weavile, Rayquaza/Deoxys Legend, Muk, Sages Training TM: Junk Arm, Seeker, Twins, Rescue Energy, Almost Every Single Prime (Magnezone, Mew, Yanmega, Gengar, etc.) CoL: Jirachi, Pachirisu, Cleffa, Tyrogue, Ninetales, Sages Training, Professor Oaks New Theory BW: Emboar, Reshiram, Zekrom, Cinccino, Reuniclus, Zoroark, Pokmon Communication, Professor Juniper EP: Pokmon Catcher, Tornadus, Gothitelle, Cheren This is just an introductory list, but Im sure just by looking at it its easy to see how tough it can be to build a deck