After 26 years of Ash Ketchum being the main protagonist of the Pokemon anime, he has — metaphorically — passed the baton to Liko in Pokemon Horizons. Liko is the first female protagonist (unlike the other female companions like Misty or May) and gets to drive the plot forward instead of just getting an occasional episode focusing on her.
In this article, we will closely examine how Liko is an improvement on Ash Ketchum and how the writers have learnt over the years. However, there are examples where Ash Ketchum has left a stronger impression on fans, perhaps due to his imperfections compared to Liko, which we shall discuss as well.
Why is Liko a better (or worse) protagonist than Ash in the Pokemon anime?
1) Better: Liko is nowhere near the brat Ash was when he started out

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Ash, at the start of his journey to become a Pokemon Master, was, for lack of a better word, a brat. While he cared for his friends and Pokemon partners, he would often get in fights with them (mostly Misty). This bratty behavior did have consequences; for example, his Charizard in the Pokemon anime did not listen to him for a long time.
Liko, on the other hand, is more caring, and her awkwardness comes off as a result of not being very social instead of her being rude. This actually makes her a likeable protagonist to follow from the start, compared to Ash, who at times could be less compelling than the world he lived in.
2) Worse: We get to see Ash learn from his mistakes and become a better person

The Pokemon anime was rather unique compared to other animes of the 90s. Ash never won a tournament until the Alola league, and this became quite a gag among fans. In kids' shows of the 90s, the hero often had the fate of the world on their shoulders and couldn't afford to lose. So the fact that Ash faced consequences for his behavior was a good lesson for kids to learn.
In the Top 16 match, where Ash fought against Ritchie, he was forced into a situation where he had to bring out his Charizard, who was not listening to him. And he lost as a result. He was arrogant and thought that just doing what he had done so far would be enough. He failed to work with his Charizard, and when he had to rely on it in a clutch moment, it backfired.
Ash learnt and grew. He became a better trainer and less of a brat, and eventually the best trainer in the world.
With Liko already starting as a likable protagonist, she is unlikely to have the same kind of character arc with so much growth potential. Liko’s arc of learning to stand up for herself is a relatively common anime trope.
For instance, Fruits Basket's plot centers around protagonist Tohru Honda’s efforts to stand up for what she loves. Similarly, Hinata from Naruto also needed to grow up and learn to become stronger. This sort of similarity makes her journey less unique than Ash's.
3) Better: Liko can focus on all her Pokemon, as there are fewer of them compared to Ash

Even in the early days of the anime, it didn't take much time before Ash had captured more than six Pokemon. This led to several of his mons barely getting screentime before either being released or sent to Professor Oak's lab. For example, Ash's Butterfree, between its evolution and eventual release, only had four on-screen appearances.
At the moment, Liko has only three Pokémon: her Meowscarada, her Hattrem, and her Terapagos. All three of them have been allowed to develop their personalities and feel more like characters as a result, instead of plot devices.
4) Worse: Liko is unlikely to get as long a run as Ash did as the anime's protagonist

For a long time, the fact that Ash was the protagonist of the Pokemon anime in an unchanging fashion was the source of many jokes. It also caused some frustration in the fandom. With Liko, the writers seem willing to make more creative decisions, like aging up the character after a time skip.
However, this also indicates that Liko might not be the protagonist of the Pokemon anime for a very long time. If the showrunners are willing to make such drastic changes to the character, they could replace her with someone else for subsequent seasons.
Liko could end up feeling less powerful compared to Ash if the writers decide to end her story and focus on a new protagonist. Ash's story, in the end, benefited from how long the writers stuck with him, despite all the jokes.
Also read: Weakest fully-evolved Pokemon of every generation, ranked
5) Better: Liko's story is narrative-driven, as opposed to Ash's badge collection quests

Ash's storylines in the Pokemon anime have been fairly easy to follow. Collect badges or climb up the ranks and face off against trainers in a tournament. While this helped to build anticipation, it could often make many episodes feel pointless as they didn't focus on the main plot.
Liko is caught up in a story-driven plot, focusing on her grandmother's pendant and how her ancestry ties into everything. She is forced to deal with events and her character sees a lot of development because of these. This focus on building a story makes each episode of the Pokemon anime far more thrilling as it contributes to the plot and Liko's story.