The Card Clubs
Card Clubs are about the same as pokemon gyms, Except they duel with cards instead of pokemon. If you get all 8 club medals you get to battle the grandmasters: Courtney(fire), Jack (ice), Steve (lightning), and Rod (dragon)
The Pokemon Dome!
The Masters of the Pkmn TCG are waiting here to battle you! Luckily, I've prepared a battle guide for you!

Courtney: Mistress of Fire
Legendary Moltres Deck
Main Pkmn: Legendary Moltres, Ninetales, and Arcanine
Courtney uses Moltres' Pokemon Power to stocke her fire types with tons of fire energy, Water type cards ought to douse her strategy!

Steve: Master of Lightning
Legendary Zapdos Deck
Main Pkmn: Legendary Zapdos, electabuzz, and a regular zapdos
His Pokemon are over powering but cards with resistance to electric will help.

Jack: Master of Ice
Legendary Articuno Deck
Main Pkmn: Legendary Articuno, dewgong, and chansey
Jack uses his chansey as a wall to take damage for him and then he heals it with pokemon center. This can get very frustrating! I recomend tons of electric types and especially the pikachu witht the attack spark to damage opponents while they're on the bench!

Rod: Grandmaster!
Legendary Dragon Deck
Main Pkmn: Legendary Dragonite, gyarados, and lapras
The use of a grass/electric type deck should help- A good grass type is pinsir!

Ronald: Rival Showdown!
Legendary Ronald Deck
He has every legendary card in his deck! You're on your own pal!

Imakuni
Imukuni is a very strange person who hangs out in the lobbies of card clubs if you beat him he gives you one of each booster pack and if you beat him enough he'll give a promo with him on it! The Card Reads:
Your pokemon is now confused. Imakuni wants you to play him as a pokemon, but you can't. He goes around the world asking kids, "who is cuter, pikachu or me?"
Ok, so the promo is pretty useless but it's nice to have around.