Which format is the best one to start off with once you know the rules
But Im not here to waste your time going on about flavor (not right now, anyway)
It doesn't see play in the competitive Modern format, but casual and Commander decks can get use out of it
While the feel of modern new and fake cards are very similar (smooth and polished), an old, real card is supposed to be rougher to the touch
By the same token, "Blue" ( Mythical Island ) reduces the damage your Pokmon take from attacks next turn by 10, which can sometimes make the difference between your Active Pokmon being knocked out or surviving
If Pokmon cards drive you to victory and Trainers are the oil that keeps the deck flowing, then Energy cards are the fuel that kickstarts the machine