As the player character's rival, he fights the player from time to time during the normal course of the gameplay. He plays four different decks as the player progresses through the game.
I'm Ronald Deck
After the player obtains the second Master Medal, Ronald will appear in the lobby of the club and battle the player with the I'm Ronald Deck. The player only has one chance to win this duel. Should the player be successful, the player will earn a promotional Jigglypuff card.
After the player obtains the fifth Master Medal, Ronald will appear in the lobby of the club and battle the player with the Powerful Ronald Deck. The player only has one chance to win this duel. Should the player be successful, the player will earn a promotional Super Energy Retrieval card.
During the story of the game, there are two Challenge Cup matches. One takes place between the player's third and fourth Master Medals, and another occurs between the sixth and seventh. Ronald is the third opponent the player must face, and he will be using the Invincible Ronald Deck.
If the player defeats Ronald during the first Challenge Cup, the prize is a promotional Mewtwo card.
Ronald appears several times during the game. In the beginning of the game, when the player enters a club building for the first time, Ronald talks about Team Great Rocket, and uses the Card Pop! function with the player. He also appears after defeating Miwa at Psychic Club, and if defeated, he gives the player a rare Super Energy Retrieval card.
Ronald is met again on the GR Island when entering Game Center for first time, as Ronald appears and gives away the Bill's PC card. Shortly after that, he may be seen again at the GR Grass Fort, now belonging to Team Great Rocket as member GR-X. He then challenges the player to a 6-prize match, in which he uses a deck focusing on Pokémon. When defeated, he reveals his identity and mission to recover the cards stolen by Team Great Rocket and gives one of both Team Rocket's Ambition and We Are Team Rocket booster packs.
"Well, getting the <club> Medal wasn't that hard! If I keep this up, I should be able to get the Legendary Pokémon Cards!"
"What? It's you, <player>! What are you doing? Huh? That's a deck! Are you... trying to get the Legendary Pokémon Cards?"
No:"It's useless trying to hide it! I know you came here for the Medal! You're out of your league!"
Yes:"What!?! I can't believe it! You? The Legendary Pokémon Cards? Ha ha ha ha ha! Don't make me laugh!!!"
"Alright! Listen up! I'll teach you what it's about! To inherit the Legendary Pokémon Cards, you must defeat the 8 Club Masters and get the 8 Medals! Then you have to go to Pokémon Dome and defeat all 4 of the Grand Masters there!!! There's no way you can do it!!! You might as well just give up and go home! 'Cause the Legendary Pokémon Cards are gonna be mine! I already won the first Medal! See ya, <player>! Ha ha ha ha ha!!!"
After the player earns his/her second Medal
"Hi, <player>! How ya doin'?"
"So you won the second Medal? You must have been really lucky!"
"I'll see how good you really are! Come on, let's duel!"
"We'll play with 6 prizes! If you win, I'll give you a really rare card!"
When defeated (first battle)
"I... I wasn't really trying that hard!"
"Well, a loss is a loss, so I'll have to give you this card."
"It won't be so easy next time! See ya!"
When viewing the Plate of Legends before all Medals have been earned
"Hi, <player>. What are you doing here?"
"Yes! The Legendary Pokémon Cards will be inherited here at Pokémon Dome! Of course I, Ronald, will inherit the cards!"
"Hey, did you collect the Medals?"
Yes: "Hey, <player>! You only have <number> Medals!"'
"I've already collected <number+1>! Why don't you just give up? See ya!"
No: "Duh! That's pretty obvious! There's no way you could collect them all! Why don't you just give up? See ya!"
When met in Challenge Hall
"Hi, <player>! Are you competing in the Challenge Cup, too?"
"I'm the one who's going to defeat 3 opponents! The prize, LV60 Mewtwo, belongs to me! You just sit tight and watch me win!"
Ronald appears as the main character in Pokémon Card GB The Comix, a one-shot manga based on the video game of the same name. In Pokémon Card GB The Comix, Ronald duels his rival Mark, but ultimately loses.
Ronald uses the following Pokémon cards in his duel against Mark:
Seel → Dewgong
Dewgong is a Water-type card used by Ronald in his deck. Ronald began the duel with Seel as his Active Pokémon. On his second turn, Ronald Evolved Seel into Dewgong. As Dewgong, it Knocked Out Mark's Scyther using a combination of its Aurora Beam attack and PlusPower. Eventually, Dewgong was Knocked Out by Mark's Ivysaur.
Magmar is a Fire-type card used by Ronald in his deck. Magmar was placed on the Bench on Ronald's fourth turn, and became the Active Pokémon on his fifth turn after Dewgong was Knocked Out. Magmar had the advantage over Mark's Ivysaur (and then Venusaur after it Evolved) due to the type advantage of Fire over Grass. However, it was Knocked Out by Mark's Charizard after it was swapped out from Venusaur.