Theyre indeed an official product, released by Wizards of the Coast, and are copies of Constructed-legal cards
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
Definitely recommend this
Its giving Pattern of Rebirth vibes, though it could miss on the mill trigger
