The live-action Pokemon movie in the works is almost assured to be an adaptation of the anime, not the game series. A new adaptation of the games would be amazing, but that probably won’t ever happen. Pokemon Adventures, also published as Pokemon Special, is a comic based on the game series as a whole and has the best storyline of any Pokemon adaptation. There are several story elements in Pokemon Adventures that would be great to see a live-action film series.
One: Gym Leader Civil War
In Adventures, the Kanto gym leaders are split into two different factions: a group of Team Rocket officers and an opposing group allied with Red, the game/comic protagonist. That plotline added realism to the world building and provided compelling and dangerous villains to the story without the need to create new characters.
Two: Physicality of Pokemon Training
In contrast to the turn-based game system, in Adventures Pokemon battles are incredibly complex and violent fights that require tactics and physical strength from the trainer. Trainers use lot of tricks in combat. Bruno actually treated pokemon training as a martial art trained with his pokemon. That portrayal of battles also adds realism and made fight scenes much more intense and interesting.
Three: Some Humans Have Powers
Several humans in Adventures have superhuman abilities. A notable example is yellow who was granted psychic powers by the “Viridian Forest” allowing her to communicate with Pokemon and heal them. Giving humans supernatural powers played up the fantasy elements in the Pokemon universe.
Four: Cater To A Wide Audience.
There are at least thousands of people who grew up with Pokemon who and are now in their 20s. They are a significant target audience for a movie. Adventures did a wonderful job of making the story accessible to kids and appealing to a wider more mature audience.
With all these elements incorporated in the production, a live-action Pokemon movie would amazing. A lot of people would be interested in it. Hopefully Legendary Pictures has some of this ideas in mind.