A match in the Battle Arena pits two Pokémon against one another for three rounds. If both Pokémon last all three rounds, they are rated on how they battled in three aspects, and the Pokémon with the higher score wins, and the losing Pokémon leaves battle. If they somehow tie, both Pokémon leave battle. A knockout results in an automatic win for the Pokémon that is still standing. Trainers are not allowed to switch out their Pokémon, and they must be sent out in the order they were entered.
Pokémon are scored on their mind, skill, and body. This is much like the Fallarbor TownBattle Tent rules. The Pokémon with the better rating in each category scores two points, while a tie will award one point to each Pokémon.
Mind judges Pokémon on their offensive style. One point is awarded if a move that deals damage is chosen for use (except Counter, Mirror Coat, and Bide, which do not award points, and Fake Out, which deducts one point), and one point is deducted if Protect, Detect, or Endure is chosen. All other moves do not award points. Only the move selection matters; even if the Pokémon does not actually use the move (due to an effect such as paralysis), it will still score in this category. The Pokémon with the higher number of points wins the two points in the overall judgment.
Skill judges Pokémon on accuracy. One point is awarded if any move is used successfully, while two points are deducted if the move misses, fails, or is prevented from executing due to an effect such as paralysis. If the move was caused to fail by Protect, Detect, or flinching from Fake Out, however, no points are deducted. Hitting a move super effectively rewards two points rather than one, but dealing not very effective damage instead deducts one point. The Pokémon with the higher number of points wins the two points in the overall judgment.
Body judges the amount of HP remaining at the end of the third round compared to their amount at the start of the first. The Pokémon with the better ratio wins the two points in the overall judgment.
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After 28 wins and 56 wins, Arena Tycoon Greta appears to challenge the player. On her defeat, she awards the player with the Guts Symbol.
Before the match begins, the challenger must use a special wheel machine to randomly decide whether the match will be one-on-one, two-on-two, or three-on-three, and both Trainers send out all of their Pokémon, which are only recalled once they've been defeated or the battle ends.
In Ash's case, the wheel landed on two-on-two. Although Ash's Grovyle was defeated by Greta's Hariyama, Ash's Snorlax managed to defeat both of Greta's Pokémon, despite being at a type disadvantage against both of them, giving Ash the victory and earning him the Guts Symbol, his second Frontier Symbol.
Pokémon used in the Battle Arena
The following is a list of Pokémon used in the Battle Arena:
Hariyama was the first Pokémon used by Greta in her battle with Ash, where it first battled with Ash's 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 Harden. Eventually, Hariyama was 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 dodged it and hit it with Focus Punch.
Just when it seemed it was all over for Ash, he 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.
In Sneaky Like Shedinja, Emerald challenged the Battle Arena as his fourth Battle Frontier facility during the Battle Frontier's seven-day opening ceremony. His battle against Greta eventually came down to a match between Greta's Shedinja and Emerald's Sudowoodo. Thanks to Emerald's cheering, Sudowoodo was able to withstand Shedinja's Solar Beam, and the match was judged in Emerald's favor, making him the winner and earning him the Guts Symbol.