Cheats for Pokemon Trading Card Game 2: Great Rocket Visits (GBC)

Better card pop card with your rival
Save the game before you card pop with your rival. If you do not like the card, turn off the Game Boy Color and try again. Repeat this as many times as needed.

Arcanine card
Look at the Base Set 1 Arcanine. In the American Wizards Of The Coast card it is an "Uncommon" card, but here in the game it is "Rare"

Dr. O-Yama's Web Page
Use this option on the PC in the game to rate your decks and get tips.

Cards for cards
When you get to the Pikachu Gambling Center on Great Rocket Island, go to the big machine. For five tokens you can send five cards to Dr. O-Yama. If he likes them, he may get good cards for mail. Note: Once you mail him these cards you cannot get them back.