After winning his first regional Pokémon League and becoming the Alola Champion, Ash returns to Pallet Town. Eventually he goes to Vermillion City where he meets Gou and together they become a researcher duo.
Both Ash and Gou have different goals.
Ash eventually decides to participate in the PWC aka the Pokémon World Championships (which was teased in the Diamond & Pearl series, gotta love some forshadowing!) where Ash eventually wants to enter the Masters Eight, which are the eight strongest trainers in the world with Leon being the number 1.
Gou wants to meet Mew and does so by catching as many Pokémon as he can. Honestly, I needed some time to get used to him but I eventually learned to love him. At some point he also joins Project Mew which is a group of people that want to find Mew but not everyone is allowed to join. The people who want to join have to collect Mew tokens and only if you have the right amount of coins, you can join. Because of this Gou does have a few rivals like Tokio and even Gary, Ash's old rival.
Overall I loved the series. It's not like all the previous Pokémon series where Ash just stays in one region. Ash and Gou go to every region, including Galar, the only one of these regions that Ash has never fully discovered. Because of this we do see older characters returning like Iris, who now the Unova Champion (and member of the Masters 8), Dawn (who still does contests) and more.
Ash doesn't really have a rival like he usually has. His 'main rival' is basically Leon since that's the one he wants to beat. The only other trainer that comes close to being a rival is Bea.
There are a lot of things I didn't like. I didn't like how they didn't spent more time in Galar or how there weren't more two parters and the pacing felt very off too at times. Ash jumped many spots in his PWC ranking at once. I wanted more PWC battles. I hated Team Rocket's treatment.
Luckily there are more things that I did love. Ash and Gou are a great duo. Koharu is a great addition but she deserved better. Ash becoming the world champion was so satisfying and I cried when it happened. Ash vs Leon is the best battle in the entire history of the Pokémon anime and I don't think they'll ever be able to top this (to be fair, I did say this about Ash vs Kukui too....)
Seeing all the character returns and cameos was a blast. I grew up with this anime since 1999 and it means the world to me. It's clear that this series wasn't just catered towards kids but also to the adults who grew up with this show. This is the last full series with Ash as the main protagonist and it's clear they wanted to celebrate his past with this series.
Overall a great show, my second favorite Pokémon series.
