Pokémon Trading Card Game/Grass Club

The Grass Club is an all-girls club of Grass type Pokémon decks. This makes it an effective starting point for players who choose the Charmander and Friends Deck to start. It's a clear analogue to the Celadon City Gym in the mainline games. The club master Nikki isn't here right now, and her club members won't tell you where she is until you defeat all of them.

Kristin
She is on the eastern side of the Grass Club's main hall. Her deck is composed of mainly Grass type Pokémon that are weak to Fire leading to easy wins for Fire type focused decks.

Lickitung being the only Colorless type Pokemon in her deck can be a great stalling opportunity for her with it's 90HP and chance for paralysis with just a single Energy of any type. Stalling is probably the only way her deck is a threat though. She has three thin Stage 2 lines in her deck and she'll probably never see all three in one of the lines in the time a match takes if you avoid getting paralyzed.

There is still the small chance she'll use Pokémon Breeder on a Basic Pokémon to evolve it directly into its Stage 2 counterpart or evolve them in consecutive turns. At that point it's your biggest threat and you'll want to focus on starving it of Energy and hitting it hard or you may not survive.

Generally speaking though, you should win more than 50% of your matches against Kristin because her deck just isn't designed well.

Heather
Heather is right in front of you when you enter the main hall.

Her deck is centered around her Eevee. She wants to get them into play, then evolve them into Flareon, Jolteon, and Vaporeon. If your deck is entirely Fire type Pokémon then Vaporeon in particular will be problematic. Overall they manage to cover each other's weaknesses pretty well.

Her Venomoth has a Pokemon Power that lets it become the same type as any other Pokemon in play. This makes it easier for it to hit for weakness on your active Pokemon and a chance to cause the poison and confusion status effects all at once. This can be devastating if you're not able to take care of it quickly with a Switch or Full Heal.

Brittany
She is in the Grass Club lounge at the table.

You do not want her to get her Jynx set up to use Meditate. Knock it out as soon as possible if she puts it in play.

The rest of her Pokémon are pretty weak, and have many different types making it difficult for her to get the right energy to use their most powerful attacks. The problem that comes up is that they like to cause the Paralysis status condition, preventing you from attacking on your turn unless you have a card like Full Heal, or Switch with another Pokémon who is ready to fight on the bench or one with free retreat to get your attacking Pokémon back in the active spot.

You want to strike quickly because Brittany will be at an advantage in the late game when she has access to the right types of energy.

Club Master: Nikki
Once you have defeated all three of the other members of the club, they will tell you that Nikki has gone up to Ishihara's house. The house in the northwest of the map will now be called Ishihara's House and you can go there to find Nikki. She says she was doing research and heads back to the club to be able to duel you. She will be at the north end of the room Kristen and Heather are in.

Nikki's deck is a more focused version of Kristin's deck. It drops the Lickitung and Victreebel lines and uses an Exeggcutor line in place of the Tangelas. This makes it a fair bit more dangerous since her deck has good synergy. It also gives her a couple better Trainer card choices.

Her Oddish is annoying because it can paralyze your active Pokémon on a coin flip each turn, but when it evolves into Gloom or Vileplume, they are powerful but with confuse themselves with their attacks. This causes a chance for them to not be able to hit you on consecutive turns if they get a tails on their confusion check trying to attack.

Exeggutor is dangerous if he gets enough energy on it, so make sure to take out the Exeggcute's before they can evolve, or starve Exeggutor of energies to keep it from getting too many coin flip opportunities.

If you let her evolve one of her Bulbasaur all the way to a Venusaur and there are enough energy spread around her board, you've likely already lost. The Energy Trans Pokémon Power lets her move her Grass Energy around however she wants. It's Solarbeam is extremely powerful doing 60 damage by just moving 4 Grass Energy to Venusaur itself, but it can also move all of the Grass Energy on her board onto Exeggutor to get enough heads coin flips to knockout each of your Pokémon. On the flip side, if all her Energy end up on one Pokémon, the knockout of that Pokémon will be devastating to her board.

A victory over Nikki results in you obtaining the Grass Medal.

Card Trades
There is a girl in the lounge of the club who wants an Oddish Lv.8 card. She'll trade you a Vileplume Lv.35 card for it. You can get Vileplume in the same Mystery booster pack that you can also find the Oddish in so this isn't a unique trade you absolutely must do, but it is a nice trade of a common for a rare if you're struggling to find a Vileplume.