1. Kanto Generation – Where It All Began

As Ash’s hometown, Kanto is also where Ash started his career. However, right now he was still just an inexperienced rookie. However, what Ash did was not bad at all. During his battle with Ritchie at the Kanto tournament, Ash used Butterfree, Charmander, and Pikachu, before Charizard became disobedient and forced Ash to surrender.
In this generation, Ash has caught quite a few Pokémon such as Kingler, Pidgeotto, Primeape, Muk and Tauros; but he doesn’t use them very much. Bulbasaur and Squirtle are two of his familiar choices, but not evolving has put Ash at a great disadvantage. Relying on Charizard harmed Ash when it was needed most, and Snorlax and Lapras joined him too late.
2. Sinnoh Generation – where Ash became more mature

4th generation – Sinnoh, is also the time when Ash becomes more mature. He started to learn more from his mistakes and build a more philosophical squad. Ash now evolves both Turtwig and Chimchar into Torterra and Infernape; make this duo even more important. In addition, Buizel receiving Dawn also helps Ash a lot.
Besides, capturing Staraptor and Gliscor and adding Gible makes Ash a good team, even though Gible hasn’t evolved into Garchomp. In the Sinnoh tournament, Ash overcame his opponent Paul with his very strong lineup. However, viewers are still a bit sorry for Ash because he was unable to defeat Tobias when he possessed the duo Darkrai and Latios, legendary Pokémon.
3. Alola Generation – First Championship

Victory at Alola was Ash’s first real victory at a Pokémon tournament. In theory, his squad shouldn’t be too strong when Rowlett hasn’t evolved, Torracat hasn’t reached the final level yet. However, both show the courage and determination to defeat their stronger evolutions Decidueye and Incineroar.
Ash also possesses an impressive Lycanroc when he defeats Gladeon. Most importantly, we have to mention 2 Ultra Beasts – Melmetal and Naganadel. This is a worthy duo when playing a big role in this tournament. In the end, sure, Pikachu deserves to be honored as Ash’s trump card for so long.
4. Generation of Kalos – Many impressions but regretful ending

At Kalos, Ash is extremely confident because his squad is very strong. Along with Pikachu, Ash has owned an extremely great squad, including Talonflame, Hawlucha, Goodra, Noivern and especially Greninja.
Throughout the Kalos journey, Ash has shown great determination and demonstrated some creative strategies in utilizing the specific strengths his team possesses and this was further demonstrated at Kalos tournament. Despite losing to Alain in the final, Greninja and Ash deserve some respect, even though many expected Ash to win the tournament more.
5. Generation of Pokémon Journeys – A Well-Deserved Championship

In Pokémon Journeys, viewers can feel that Ash has built the perfect squad. He demonstrated his ambition to become a champion, and indeed did so by convincingly defeating Leon.
Along with his new friend Goh, Ash used an impressive lineup, including Gengar, Dragonite, Lucario, Dracovish, and Sirfetch’d. These are all advanced and very powerful Pokémon, along with Pikachu – Ash’s hardcore. At this tournament, Ash really showed himself when he overcame a series of the strongest names like Cynthia and Leon. This is a well-deserved achievement for Ash after his very long journey towards the world championship.