"I don't know how to say it, but... To put it bluntly, you look pretty weak. Are you sure you're up for me? Hmm... Well, all right! We'll take things easy to start with! Okay! Let's see you ignite my passion for battle!"
"No way! Good job!"
If the player is defeated
"Oh, come on! You have to try harder than that!
After being defeated
"Ow, wait a second! You are tough after all! I like you! Let's see your Frontier Pass."
"It's going to be fun the next time! I'm looking forward to it!"
"Hey! Howdy! You finally won your way up to me! I was getting worried waiting for you! I was really looking forward to seeing you again!"
"... ... ... So, are you ready?"
"I won't allow a halfhearted effort! Be ready for a thrashing! Come on, referee! Let's get this started!"
"Huh? Are you serious?!"
If the player is defeated
"Heheh! What did you expect?"
After being defeated
"Gaaah! Blown away! Let's see your Frontier Pass!"
"Arrrgh! This is so infuriating! If we ever battle again, I won't lose! Don't you forget it! Bye-bye!"
Ash spun a two-on-two match. His Grovyle was defeated by Greta's Hariyama in the first round. Ash's Snorlax, using its impressive endurance and equally powerful attacks, went on to defeat both of Greta's Pokémon and earn Ash the Guts Symbol.
Greta, like Ash, is a high-spirited individual and very passionate about Pokémon battles. Like her role models Chuck and Brawly, she continues to train her focus in order to improve her strength.
Speed-based strategies work poorly against Greta's team, and they actually help magnify her Pokémon's attacks. Her Pokémon's own speed and relentless physical moves make Greta a tough opponent. However, her Pokémon are weak to attacks from above or behind. They also tend to suffer severe injuries whenever they miss their target.
This listing is of Greta's known Pokémon in the anime:
Hariyama was the first Pokémon used by Greta in her battle with Ash, where it first battled with Grovyle. Despite that Grovyle managed to outmatch Hariyama in speed and deal some damage on it, Greta was finally able to use Grovyle's momentum as her own advantage, and land a critical hit on the Wood Gecko Pokémon, knocking it out.
Ash next used his Snorlax against the Arm Thrust Pokémon. Despite having disadvantage in type, Snorlax was able to keep itself safe from Hariyama's attacks by using Protect. Eventually, one of Hariyama's Arm Thrusts missed its opponent and it instead punched the battlefield, leaving it with a sore hand. It was frozen solid and knocked out with an Ice Punch.
Greta chose Medicham, along with her Hariyama to battle Ash in Wheel of Frontier. It was the second to go up after Hariyama was defeated by Ash's Snorlax. Medicham overwhelmed Snorlax with its astounding speed and agility. With Ice Punch, Medicham was able to freeze Snorlax giving Greta a huge advantage.
Ash then commanded Snorlax to use Rest, and Greta told Medicham to attack Snorlax with repeated Focus Punches in order to break the ice. Greta told Medicham to use High Jump Kick but Snorlax managed to dodge it, causing Medicham to take some damage. Snorlax then tried to attack it with a Hyper Beam, but Medicham evaded it and retaliated with Focus Punch.
Just then, Ash commanded Snorlax to use Hyper Beam on the ground which catapulted it into the air. Using its altitude to his advantage, Ash told it to attack with a full-on Body Slam, defeating Medicham and earning Ash the Guts Symbol.
Greta is one of the seven Trainers hired by Scott to be a Frontier Brain at the Battle Frontier. Greta is first seen hosting the Battle Frontier's opening ceremony. The ceremony is interrupted by Emerald, who announces that he wishes to conquer the Battle Frontier. The press mistakenly report the incident as allowing an ordinary Trainer to take part in the Battle Frontier before it officially opens a week later. The Frontier Brains decide to use this assumption as free publicity and allow Emerald to challenge the Battle Frontier under the condition that he completes it before it officially opens.
Later, while Emerald is challenging the Battle Pyramid, Noland is attacked by an unknown assailant and several rental Pokémon are stolen. After Noland is taken to a hospital, the other Frontier Brains begin to suspect Emerald as the culprit. They head to the Battle Pyramid to confront Emerald and find him after having defeated Brandon. When they ask him about what happened, Emerald reveals that he did not attack Noland and is actually after the Mythical Pokémon Jirachi. The Frontier Brains find Emerald's explanation suspicious, but decide to follow him into Artisan Cave, where Jirachi is currently located at. Upon arriving, everyone is attacked by a horde of wild Smeargle while Emerald continues inside to find Jirachi. After the Frontier Brains get past the Smeargle, they meet up with Emerald, who has managed to find Jirachi. Emerald attempts to capture Jirachi, but is attacked by Guile Hideout, the actual culprit who attacked Noland.
Emerald is attacked by Guile's stolen rental Pokémon, but he refuses to fight them and continues to head after Jirachi. When Greta sees this, she angrily tells Emerald that stopping Guile is more important than Jirachi and goes off to help the others. When Spenser, Lucy, Tucker, and Brandon are defeated by Guile, Greta steps in to help and defeats the rental Pokémon. Eventually, Jirachi escapes, forcing Guile to leave to continue his pursuit of it. Injured from the battle, everyone decides to return to the Battle Frontier. Upon arriving, the press demand to know where the Frontier Brain's had gone and why they were injured. Tucker lies to everyone that they were all in training and sends Greta to have her battle with Emerald.
At the Battle Arena, Greta is Emerald's fourth opponent, and Emerald is allowed to battle her directly. Both sides fight hard, but Emerald eventually emerges as the victor, earning himself the Guts Symbol in the process. The battle leaves Emerald so exhausted that he and his Pokémon fall asleep. Greta brings Emerald and his Pokémon to the Battle Frontier's accommodations to sleep properly. When Greta and reporter Todd undress Emerald to make his sleep more comfortable, they are shocked to find that Emerald is much shorter than he initially appears. Todd kicks Greta out of the room and asks her to pretend she saw nothing.
The next day, Greta assists the other Frontier Brains in ushering people to the Battle Dome. During the tournament, Guile appears and manages to capture Jirachi. Guile uses the rental Pokémon to the attack innocent bystanders and heads to the Battle Tower to make his wish. Once he arrives at the Battle Tower, Guile uses Jirachi to wish for a gigantic Kyogre made of seawater to flood the entire Battle Frontier. Greta and the other Frontier Brains work together to get civilians to safety and fight off Guile's rental Pokémon while Emerald and the other Pokédex holders fight Guile. Eventually Emerald and the Pokédex holders manage to defeat Guile and destroy the gigantic Kyogre monster. The day after, an injured Greta and the other Frontier Brains congratulate Emerald for the hard work he put into saving everyone.
Greta and the other Hoenn Frontier Brains battle and defeat the Admins of Neo Team Magma and Neo Team Aqua, who had interfered in the launch of a rocket that was made to stop the meteoroid threatening to destroy the world. Greta attempts to interrogate the Admins on the location of their accomplice, Zinnia, only for the Admins to deny knowing where she had gone.
Umbreon is Greta's first known Pokémon. It was first seen at the Battle Frontier's opening ceremony alongside its Trainer. At Artisan Cave, it was used to battle Guile's army of stolen rental Pokémon. At the Battle Arena, Greta used Umbreon as her second Pokémon. It managed to defeat Emerald's Dusclops, but was defeated by his Sudowoodo.
Shedinja is Greta's second known Pokémon. It was first used at the Battle Arena to battle Emerald. There, it was the third Pokémon Greta used and battled Emerald's Sudowoodo. Despite its single hit point, Shedinja managed to defend against Sudowoodo's super-effective hits and fight back. Despite this, Sudowoodo survived Shedinja's attacks, allowing it to win via assessment.
Heracross is Greta's third known Pokémon. It was first used at the Battle Arena to battle Emerald. There, it was the first Pokémon Greta used and battle Emerald's Sceptile. Although Sceptile survived Heracross's Megahorn, it was defeated via assessment afterward.