The Unbeatable Lightness of Seeing! (Japanese: ハルカＶＳシュウ！ライバルよ永遠に May vs Drew! Rivals Forever) is the 42nd episode of Pokémon: Battle Frontier.
Max asks when is he going to start his training, but Ash does not know - he shouldn't wait too long or too soon. May's Skitty and Beautifly try to cheer May up, but with no effect. Still, she turns to them and begins to practice. Brock and Scott see her and know she is feeling sad because of her loss at the Grand Festival. Scott tells the more the person is experienced, the more obstacles it must evade. Skitty uses Blizzard and Beautifly Psychic, controlling the attack. Ash and Max come and see Beautifly and Skitty. May tells Beautifly learned to use Psychic. She asks Ash how is his training going, but he does not know what to do. Max has an idea - they should battle each other as a practice. May disagrees, as she thinks Ash is too powerful for her.
Prof. Oak comes and everyone recognizes him. Prof. Oak brought a bag - the Pokémon at the lab heard of Ash's loss and they made something - a large plaquette, which has colors of the marks of every Pokémon Ash has at the lab. Also, Oak gives him lunch from his mom, a fishing lure from Misty and, lastly, a postcard from Gary, who is traveling in a region north of Kanto, Sinnoh. Ash has a vision of him and Gary - Gary tells he will not waste his time on someone who will give up, so Ash tells he will not waste more time and re-gains his confidence. Oak meets Scott and tells Ash needs them all. Oak tells his newest poem and Nurse Joy spots him, being dazzled and wants an autograph, one that Oak gives to her.
May sees Ash so confident and thinks they are lucky. She spots Roselia and Drew and Nurse Joy wants an autograph from him as well. May tells she was thinking of him and there he was. May tells she was fine after the loss at the Grand Festival, while Drew responds he was taking care of his own Pokémon. Drew knows May is still sad from the loss (despite her words) and tells her she does not know what to do next. To make her feel better, Drew proposes May a battle. May is unsure, though Ash, Brock and Max tell her to go for it. May is convinced, so the heroes go to ask Oak and Joy to be judges, but Raoul Contesta, Mr. Sukizo and Nurse Joy (Jessie, James and Meowth in disguise) appear.
May suspects something wrong, and Harley appears, with his Cacturne using Bullet Seed on Team Rocket. Team Rocket's disguises fall down and Harley clarifies he is the only one to mess with May - he came here to make her cry. They run away, but Cacturne stops them, as Harley tells he does not want them away... yet. He wants Jessie to fight alongside him. Max demands how will they know if Harley will not do something, so Harley promises everything to be clean. Nurse Joy, Scott and Oak came and Joy also asks for Harley's autograph, to which he gives it to her. Later, many people came and Drew and May will have a Double Battle. May sends Beautifly and Combusken, while Drew his Roselia and Butterfree.
Combusken starts with Fire Spin and Beautifly Psychic, empowering Fire Spin. Roselia counters with Petal Dance. Beautifly uses Psychic, using the flames Roselia deflected to attack, though Roselia uses Magical Leaf. Combusken charges and Butterfree uses Gust, damaging Combusken with the leaves that were put on fire with Magical Leaf and Combusken is knocked out on Beautifly. They both stand up and go to attack Butterfree. Butterfree uses Psybeam, but Combusken dodges and uses Sky Uppercut on it. Roselia uses Petal Dance, so Beautifly goes to counter with Silver Wind, but the Petal Dance merges with Silver Wind and hurts Combusken and Beautifly. Combusken uses Overheat, but Butterfree uses Protect. So, Roselia uses SolarBeam and Butterfree Psybeam, defeating Combusken and Beautifly.
May is a bit sad, but now knows what she has to do and tells Beautifly and Combusken they gave their best. Later, May confesses she was overconfident and needs to find her own battle style. Drew tells to May he will go to Johto and thinks Solidad will be there to compete in the Contests. Harley hears that last part and tells he will be in Johto as well. Harley asks Jessie if she will be there, but Jessie tells she has business in Team Rocket. Harley is angered, telling she wants to be a loser. Jessie is angered and goes to send a Pokémon, but too late - Harley's Cacturne used Bullet Seed on her, Meowth and James, blasting them off. Harley proposes to Drew and May they could go together, but they don't feel like it, resulting in Harley running.
Ash, Max, Brock and Oak come, as they heard an explosion. May explains Harley blasted Team Rocket off. Drew tells he needs to go as well and wants the next time he sees May to see the new battle style. May tells to Ash, Brock and Max Drew went to Johto region. Brock suspects as Drew and Harley came to help May. May tells that she and Ash need to work on their own battle styles, as the Battle Frontier needs to be completed.
- This is the first episode in the main series to mention Gary since his rivalry with Ash was resolved in Gotta Catch Ya Later!.
- This episode marks the first mention of Sinnoh in the anime.
- An instrumental version of Advance Adventure, background music from Lucario and the Mystery of Mew, an instrumental version of 小さきもの A Small Thing are used as background music.
- The next episode preview is narrated by Brock.
- This episode's dub title may be a reference to the book The Unbearable Lightness of Being.
- This episode marks the final appearances of Drew and Harley as recurring characters in the show.
- Professor Oak's eyebrows, which are actually brown/black, are painted gray in a few scenes.
- The color of Harley's hair when he first appears in the episode is duller than normal.
- In the sunset scene at the end, the right side of Ash's hair was white against Professor Oak's jacket.
- In the English dub Drew tells Butterfree to use Gust, but in the Japanese version, Drew tells Butterfree to use Confusion, then Gust.