In HeartGold, SoulSilver, and Platinum, Caitlin is the employer of Castle Valet Darach and oversees his Battle Castle battles. She is responsible for determining how many CP the player should receive depending on the outcome of the battle. She is said to be the most important person in the Battle Castle and acts like its princess.
In Black and White, Caitlin appears as a member of the Elite Four of Unova; she traveled to the region alone in order to develop her skills further. It is revealed that she possesses some sort of psychic powers, and that in the past, she had an explosive temper that would erupt if she lost a battle causing her psychic powers to cause a lot of damage. This may be the reason why Darach fought in her place in Generation IV. It may also explain why she is quite impatient, as she demands that Darach give the player Castle Points "at once!" after each victory in the Battle Castle.
She later appears in a villa that she is lending to Cynthia, as do the other female Gym Leaders and Elite Four members. She also mentions her time at the Battle Castle while in the villa.
"Who are you? How impudent you are to disturb my sleep. Hmf... You appear to possess a combination of strength and kindness. Very well. Make your best effort not to bore me with a yawn-inducing battle. Clear?"
During battle (the first non-KO hit)
"I get the feeling a wonderful time is about to start. I'm excited!"
After sending out last Pokémon
"Even at a time like this, I should stay cool and collected..."
During battle (less than half HP)
"For the sake of the Pokémon that believe in me, I will never give up."
When defeated
"As a Trainer, you are both excellent and elegant. Your Pokémon have class. I am very pleased to have battled you."
After being defeated
"You haven't faced all of the members of the Elite Four yet, have you? Don't concern yourself about me. Go on ahead."
General afterword
"In the past, when I battled, the force of my emotions shook me greatly. When my power awoke, I came close to destroying everything around me. That weak person no longer exists... Still, sometimes, my determination fails. Always, I aspire to wrap up a victory with elegance and grace. I invite you to be my opponent again in the future, if you wish."
If defeated last
"Somehow, you managed to defeat the entire Elite Four of the Pokémon League. Check the statue in the center of the plaza for the way to the Champion's room."
Rematch
Before battle
"Who's there? Who is so uncouth as to disturb my sleep? Hmf... It's you again. Still, you possess that combination of kindness and strength. Yet you seem stronger than before... Do be sure not to bore me with a snooze-inducing battle, is that clear?"
During battle (the first non-KO hit)
"A wonderful time is about to start. I like this moment..."
After sending out last Pokémon
"I will stay cool and collected, even though this isn't going well..."
During battle (less than half HP)
"I will not give up...for the sake of my Pokémon that believe in me."
When defeated
"As you have always been...or even more than ever...you are an elegant and excellent Trainer. Your Pokémon also have class. I am very pleased to have battled you."
After being defeated
"Alas! Even with the knowledge and skill passed down in my family of Trainers, I still can't win. The reason I came here in the first place was to encounter Trainers like you..."
General afterword
"In the past, my untrained heart made my power run wild. I was forbidden to battle. All I craved then was to experience the pure excitement of battling like this. Hee hee... Although I'm embarrassed, I can't help smiling right now."
If defeated last
"You have defeated the Pokémon League's Elite Four. You have earned the right to proceed to the Champion's room. Making an entrance is not the point. Once you're there, you'll need to unleash your power to the fullest!"
"Having everything go your way is the road to disillusionment. Knowing the difference between what's impossible and what's possible... I used to know someone who talked about that a lot."
"No matter how hard I try, I cannot defeat Cynthia. Before, I would have exploded with rage. Now, I have the tranquility to reflect on my performance to see how I can improve."
"Tell me something. Are you familiar with Battle Castles? You can find them in Johto and Sinnoh, so challenge them to improve yourself."
"This is my villa. I have villas all over the world, and I allow Cynthia to use them. You are welcome to come and play whenever you wish."
"Having no psychic powers at all is better than having psychic powers you can't control."
"It's me who appeared when the flower opened up. You, standing over there... You look like a Pokémon Trainer with strength and kindness. What I look for in my opponent is superb strength... I'm counting on you!"
During battle (the first non-KO hit)
"I have a feeling this battle will give my Pokémon a chance to go all out!"
After sending out last Pokémon
"I can't believe it's come to this! I must have gotten complacent."
During battle (less than half HP)
"Ohh, that's it! I'll go all out of it if I have to win!"
When defeated
"You and your Pokémon are both excellent and elegant. To have been able to battle against such a splendid team... My Pokémon and I learned alot! I offer you my thanks."
After being defeated
"You haven't faced all of the members of the Elite Four yet, have you? Don't concern yourself about me. Go on ahead."
General afterword
"---"
If defeated last
"Somehow, you managed to defeat the entire Elite Four of the Pokémon League. Check the statue in the center of the plaza for the way to the Champion's room."
Rematch
Before battle
"It's me who appeared when the flower opened up. You who have been waiting... You look like a Pokémon Trainer with refined strength and deepened kindness. What I look for in my opponent is superb strength... Please unleash your power to the fullest!"
During battle (the first non-KO hit)
"I will show you how harmonious my Pokémon and I are!"
After sending out last Pokémon
"Battling in extreme conditions like this makes me stronger!"
During battle (less than half HP)
"I will control my emotions and use them as energy to help me obtain victory!"
When defeated
"As impressive as always... No. You and your Pokémon were even more elegant and excellent than before! To have been able to battle against such a splendid team... My Pokémon and I learned so much! I offer you my thanks. Please battle me again sometime."
After being defeated
"Alas! Even with the knowledge and skill passed down in my family of Trainers, I still can't win. The reason I came here in the first place was to encounter Trainers like you..."
General afterword
"When I battle you, I can't help but smile... Because I was able to improve myself, and because you're an excellent Trainer. I want to improve and win more elegantly, so I invite you to be my opponent again in the future, if you wish."
If defeated last
"You have defeated the Pokémon League's Elite Four. You have earned the right to proceed to the Champion's room. Making an entrance is not the point. Once you're there, you'll need to unleash your power to the fullest!"
Caitlin debuted in Jostling for the Junior Cup!, where she participated in an exhibition match against Cynthia in the Pokémon World Tournament Junior Cup. Despite how powerful the two Trainers were, the time limit put on the battle ended before either of their Pokémon could be defeated, making the match a draw.
Pokémon
This listing is of Caitlin's known Pokémon in the anime:
Gothitelle
Gothitelle was used in the exhibition match for the Pokémon World Tournament Junior Cup against Cynthia's Garchomp. The two proved powerful during the fight, but neither won the battle because the time limit had ended before a winner could be decided.
Caitlin appeared alongside her valet, Darach, in the Platinum arc of Pokémon Adventures. She first appeared when she misheard Looker referring to Platinum as "Lady" as talking to her. When Looker tried to tell her about the mistake, her Gallade immediately attacked him, stripping him down to his underwear. She later watched Platinum and Darach battle at the Battle Castle and scolded Darach when he was defeated.
It is later revealed that Caitlin has gained a desire to battle after watching Platinum's battle against Darach. This desire to fight causes her latent psychic powers to awaken and go out of control while Caitlin crazily mutters the word "fight" over and over. She is calmed down by Darach when he offers her some tea.
In the Black and White arc, it is revealed that she has become a member of the Unova Elite Four.
Gallade is Caitlin's only known Pokémon and is also her bodyguard, protecting Caitlin from any possible attackers. He first appeared when he attacked Looker after he mistook the officer for an attacker when he stepped too close to Caitlin. Gallade was later used against Platinum in the Battle Castle under the control of Darach where it managed to defeat two of Platinum's Pokémon before being defeated by her Empoleon.
Caitlin is one of the few characters shown to have physically aged between game appearances.
Caitlin dresses in the Japanese 姫ギャルprincess gal style.
Caitlin is the second Elite Four member who was introduced in an earlier generation and then attained the title in a later generation, Koga being the first.
Caitlin is the only Elite Four member not from the Indigo Plateau to appear in more than one generation.
In Pokémon HeartGold and SoulSilver, a minor character in the Battle Castle mentions that Darach has feelings for Caitlin, but refuses to show these emotions to her.
Caitlin is the only Elite Four member who has more than three kana in her name.
Caitlin is the only character in Black and White who is either a Gym Leader or an Elite Four member who does not use a move introduced in Generation V in either battle.
Caitlin is one of two members of any Elite Four to have a home shown in-game, the other being Lorelei.
Apparently a reference to "Cattleya"; the name has variant spellings such as "Katelynn" that are closer to "Cattleya." It could also refer to the word "castle".
Sinnoh and Johto Battle Frontier 
