Although his journey started out a little rocky, with the majority of his major victories in Kanto coming down to pity or dumb luck, Ash has grown significantly as a trainer, in no small part due to the quality of the trainers he has to battle. Not all of Ash's opponents are particularly noteworthy, however, with some being entirely forgettable even after repeat viewings of the series.

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That being said, there are also many trainers that Ash has battled, sometimes multiple times, and are noteworthy not just in the anime series, but also in their appearances in the mainline Pokemon RPGs as well.

10 Gary/Blue

In the anime, Gary starts out as a snobbish newbie trainer who loves to rub his successes in Ash's face whenever he can. Later in the series, during the Kanto League, he suffers an embarrassing defeat that changes his perspective on himself. He changes to not only be a better person but a better rival for Ash. His video game counterpart, Blue, doesn't quite have this revelation, though he does go on to become the Viridian City gym leader after Giovanni leaves, becoming one of the strongest trainers in Pokemon Gold & Silver, only being outdone by Red.

9 May

In the anime, May starts out as a fresh-faced trainer who doesn't quite know what she wants to get out of her Pokemon career. After a few false starts, she decides that she wants to enter Pokemon Contests, where she shows a true aptitude for both standard Pokemon training and the alternative avenue available to trainers in Hoenn. While her team in the anime is quite impressive, with the likes of Glaceon, Venusaur, and an incredibly powerful Blaziken by her side, her video game presence is a little more pathetic. She may be the player's rival, but even Wally has outpaced her at every turn by the end of the game and she fails to live up to the heights of her anime counterpart in all of her appearances.

8 Paul/Silver

When it comes to Ash's main rivals over the years, there's no contest that Paul is his best by far. Not only is Paul a powerful young trainer in his own right, but his training methods are the complete opposite of Ash's, preferring raw power over love and hard work. Their final battle in the Sinnoh League is one of the best battles in the series.

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While not a direct interpretation of the character, Paul shares many similarities with Gold & Silver's rival, Silver, who not only shares a design with Paul but also a mindset in training his Pokemon for power rather than with friendship. Unlike Paul, however, Silver actually has a change of heart at the end of his storyline and might be a better rival than Blue was in Red & Blue.

7 Barry

Barry has what is practically the opposite of May's problem, being a bit of a joke in the anime but a powerful rival in Diamond & Pearl. Anime Barry also saw Paul as someone to live up to rather than an example of someone's ideals getting in the way of progress, making him a little annoying to watch whenever Paul was around. In Diamond & Pearl, Barry may not be on the same level as Cynthia, but he comes fairly close with his very impressive team that includes a Heracross and Snorlax.

6 Clemont

Brock and Misty may be the quintessential traveling companions for Ash, but that doesn't mean his other companions haven't been great characters in their own right. One such character was Clemont, who accompanied Ash across Kalos, though took a break from the team to prepare himself for his gym battle with Ash partway through the series. While his anime team was a little weird, consisting of Chespin, Bunnelby, and Luxray, his video game team was a lot closer to the team he used in the gym battle with Ash, having Emolga, Magneton, and Heliolisk. Clemont is also an example of one of the only times a gym leader traveling with Ash actually went back to their gym to do their job.

5 Gladion

gladion pokemon sun and moon loss

In Sun & Moon, Gladion is a bit of a stick in the mud that embraces his emo personality almost to a fault, though he is far from an annoying character in spite of this. In the anime, Gladion begins as a rival and later friend to Ash, with the pair's respective Lycanroc having a strong rivalry themselves. This rivalry came to a head in the Alola League finals, where Ash finally defeated Gladion after several losses over the course of the series, something players can also do in Sun & Moon. But his team is a little different from his anime counterpart's with the addition of a Lucario, Crobat, Porygon-Z, and Weavile alongside his signature Silvally.

4 Leon

pokemon sword and shield leon

So far, Leon has been presented in both the anime and in Sword & Shield as a trainer who has never lost a battle, making him one of the more imposing trainers in both iterations of the series. However, while anime Leon was able to easily defeat Ash and a newly Gigantamax enabled Pikachu, his showing in the video games is a lot less impressive.

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His game team is very impressive, with his Charizard, one of the three starters, Aegislash, Dragapult, Haxorus, and either a Mr. Rime, Seismitoad, or Rhyperior, depending on the starter chosen. However, after losing to the player, he loses repeatedly in both the Champion Cup and Galarian Star Tournament, calling the claims that he was unbeatable into question.

3 Professor Kukui

Professor Kukui in Pokemon anime

The Pokemon professor of Alola with a love of wrestling and an apparent hatred of shirts is just as imposing in the anime as he is in Sun & Moon, being the final challenge Ash must face in the first Alola League as well as the final challenge for the player in the generation seven games. However, his anime team is much more powerful than his video game counterpart. He has the likes of Lucario, Braviary, Empoleon, Venusaur, his signature Incineroar, and his final team member that came out of nowhere, Tapu Koko, who wanted to battle Ash one more time to prove its worth against Pikachu.

2 Tobias

Tobias in the Sinnoh League

Although Paul was the main rival in the Sinnoh season of the Pokemon anime, Tobias was the main threat that Ash had to face in the Sinnoh League. With the only known Pokemon on his team being a Darkrai, Tobias managed to sweep through everyone he battled with just his signature Pokemon, with Ash being the only trainer in the entire league to defeat his Darkrai before falling in a double K.O. against his equally impressive Latios. While Tobias isn't in the generation four games, the rumors of a Diamond & Pearl remake for Pokemon's 25th anniversary may see him come to the series as a rival character.

1 Alain

Ash and Alain following Alain's victory in the Kalos League

Ash's final battle with Alain was epic and climactic, though somewhat disappointing due to Ash's sudden loss. But Alain wasn't that interesting of a character, despite how powerful his team was. With his signature Mega Charizard X, Metagross, Bisharp, Unfeasant, Tyranitar, and Weavile, his final battle with Ash was evenly matched throughout the entire spectacle and the only battle in the series that is better than this one is Ash's final battle against Paul. Unfortunately, like Tobias, Alain didn't appear in the generation six titles, though there is still room for him to appear in future games if the Mega Evolution mechanic ever makes a return.

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