Aside from the increased production values, Pokémon the Movie: I Choose You! is a clearly distinct experience from the original tale. For example, Brock and Misty make no appearance within the actual film. In this timeline, Ash is joined temporarily by his new friends Makoto and Souji whilst spending most of his journey outside of the film on his own. It's the first time we have been treated to an alternate timeline within the Pokémon anime (outside of one weird Pokémon XY episode).

When the TV series' very first episode (also named “I Choose You!”) aired in 1997, an overarching plot point was introduced. A majestic bird Pokémon flew across the sky, its identity unknown to both Ash and the audience at the time. At the time, the message was simply “there are many more Pokémon to discover”, and Ho-Oh briefly appears in subsequent seasons to usher Ash along to new adventures. But the question remained: What's the deal with Ho-Oh?

I Choose You! is a Pokémon movie for classic Pokémon fans. While it features new Pokémon from Sun and Moon like Lycanroc and Incineroar, many of the stories and references are from the series 20 years ago, repurposed into far more emotionally moving encounters. Ash still finds Charmander abandoned in the rain, but this time it leads to a story of revenge and forgiveness. There's no strict requirement to have seen the original show, but there's something wonderfully nostalgic about seeing classic stories evolve into something new.

Pokémon films have often been held back by Ash's lack of character. After 20 years of adventures, his character arcs constantly retread the same ground in a way that makes him overly predictable. But while I Choose You! features the typical moments of self-sacrifice and shouting, there's more emphasis on his character arc, where he begins as a clumsy and easily provoked Pokémon Master-to-be. His moments of weakness make his strengths all the more noticeable, and the dramatic callbacks draw from 20 years of Poke-history. As a result, his character resonates far more strongly than in any previous Pokémon film.

It'd be a difficult task to count how many times Ash has been referred to as the “Chosen One” in both the films and TV series. If you've been keeping track, he's apparently the one who will restore balance to the world, an “Aura Guardian”, and the hero chosen by the lake guardians. In isolation, these are just vague plot points, but in repetition, his specialness starts to become a recurring joke. But because Ho-Oh was first introduced in 1997, the idea that Ash could be its chosen hero finally feels as if it wasn't just tacked on to drive the plot du jour. “Chosen One” is a title that is questioned, lost, and won again through a surprisingly creative character arc that culminates in a scene that veteran Pokémon fans have been waiting to see for 20 years.

Pokémon the Movie: I Choose You! has the strongest narrative arc of any Pokémon film, although there remains some odd quirks that feel unnecessary to its progression. Makoto and Souji are Ash's new teammates for this journey, but they feel more like bystanders of someone else's story, and the attempts at creating backstories for them aren't built up at all. Their personalities complement Ash well, but the lack of follow-through with their backstories only makes it more noticeable that they're mere replacements for the more recognizable characters. It doesn't diminish the experience, but it does end up feeling confusing.

The same thing goes for the appearance of Marshadow, the newest creature in the Pokémon Sun and Moon games. Seemingly taking on the role of the manifestation of all evil, protecting the darkness from the light, he appears and disappears at random moments as a deadly villain in a film that really didn't need one. It's hard to overlook that it's only there to promote the games, especially when Nurse Joy reminds the audience that they can download Marshadow onto their 3DS systems both before and after the film.

The film's strongest aspect lies within its production. Pokémon 's animation studio OLM operates using separate teams that work independently of each other. During Pokémon - Diamond and Pearl , the project was given to Hiroyuki Kato and his team, called OLM Team Kato. During his time on Pokémon , Kato invested heavily in digital animation, 3D implementation and staff recruitment, eventually creating Pokémon XY and Pokémon Sun and Moon, two visually impressive productions for the studio. For the XY series, the team worked with fully realized 3D backgrounds, allowing the animation team to work with an unrestricted camera. For Sun and Moon, they have been using more digital animation (through a collaboration with ToonBoom Animation), speeding up the workflow and giving animators more time to do what they do best.

For the 20th Anniversary, these developments have made their way to the big screen, as Team Kato takes over the role of film production from Team Kamei, the team that usually produces the Pokémon films. The results are nothing short of exciting as the film opens with a tense battle, aided by an entirely 3D world that allows the camera to follow the action more closely. 3D environments are present throughout most of the film's battle scenes, making the action feel faster and more intimate. Even outside the action sequences, the character animation pulls ahead of other entries into the series, with the first quarter of the film matching the expressiveness of the Pokémon Sun and Moon TV series.

The world of Kanto is striking and distinct compared to previous entries in the franchise . The endless forests and cliffsides have become hallmarks of Pokémon worlds, but this newer rendition captures them with a fresh level of detail and beauty. Pokémon has never felt more real than this, with huge aesthetic differences between I Choose You! and the sparser backgrounds of last year's entry to the series, Volcanion and the Mechanical Marvel.