Pokémon Trading Card Game/Fire Club

The Fire Club members use Fire type Pokémon in their decks, but most members supplement them with Colorless Pokémon as well. All of the Fire type Pokémon are weak to Water Pokémon. The Colorless Pokémon are a mix between those weak to Fighting type and Lightning type. This is probably the best club to start with if you chose the Squirtle & Friends Deck.

John
John is the first of the Club Trainers, and he uses the Anger Deck, which focuses on Fire and Colorless Pokemon cards. Water-type Pokémon Cards and Fighting-type Pokemon cards are recommended for this battle. Watch out for his Double Colorless Energy, since it allows some of his Pokemon to use their strongest attacks immediately. Gust of Wind is also annoying.

Adam
This deck is almost entirely Fire types, so a Water type deck has a major advantage here.

Club Master: Ken
Ken will refuse to face you if you challenge him with fewer than 300 total cards. Note that the count of cards on the Diary screen displays your collection count, not your total count, so is not very useful in this context. If you open the pause menu and select Card, your total amount of cards will appear in the top right corner. Once that is 300 Ken will accept your challenge. You can reach this goal fairly easily just by facing the other members several times and winning, or filling up on Energy cards with duels in ../Mason Laboratory/.

The "Charge" part of the Fire Charge deck seems to imply building up Fire type Pokémon on the bench while stalling with the Colorless type ones. You probably want to bring Fighting type Pokémon to this fight more so than the Water you would expect because of this.

Chansey is a big wall to stall you out. You'll want to get 40 damage done to it quickly on failed Scrunch flips, or be ready to retaliate with it after Double-Edge does 80 damage to your active and Chansey itself once it gets 4 energy attached. You don't want to be hit by that twice in a row. Ken does not shy away from using Double-Edge, even if it will knockout the Chansey.

The one-of Jigglypuff with Lullaby and the one-of Wigglytuff if it manages to evolve will try to stall you out by sending you to sleep. Wigglytuff is also very powerful if Ken's bench gets full, causing 60 damage for just 3 energy, and he does have Double-Colorless Energy to get there quickly.

Magmar and Arcanine do have powerful Flamethrower attacks though, so you'll want to starve them of energy with Energy Removals and Super Energy Removals, or use Gust of Winds to bring them forward and hit them hard with strong attacks from Water Pokémon as soon as possible.

Slowpoke Promo
There is a Lad in the club lounge who will tell you to come back when you have a lot of Energy cards. In reality he waits for you to earn your third master medal. Once you have the medals and speak to him he will ask you for all of your unused energy cards. If you give them to him, he'll tell you about a hidden card in the room that will now be available two tiles to the left of the bookcase. It's the promotional Slowpoke card! Refusing his request will see him run off and you won't be able to get this card until the post-game in the ../Challenge Hall/.

It's a good idea to put all of your Energy cards you can into your other deck slots before talking to this guy. However, if you now find yourself a little low on Energy cards after this, head back to ../Mason Laboratory/ where there are several opportunities to replenish your stock.