Since that has been brought up, let me recount you the intro to Pokemon Colosseum for Nintendo Gamecube:
Your character is a criminal that works for a gang of Pokemon thieves. The game starts with him setting off plastic explosives inside the base of his gang, stealing something in the confusion(the device that lets you steal Pokemon from other trainers in-game) and rides off into the sunset on his motorcycle, grinning all the way as you see panicking grunts making their way out of the building and his former boss visibly pissed.
After a short stop at the gas station, where Wes(your character) meets an eccentric Zigzagoon enjoyer, he spots 2 shady individuals making their way to Phenac City, with a big burlap sack. Wes has nothing better to do so he follows them. Once in town, he notices that the sack is moving, so he challenges the two goons and once they run off, finds a teenage girl that was casually kidnapped in broad daylight inside of it. She was being hooved off to god knows where because crime is so bad in this region that nobody bats an eye on something like this anymore. From that point on, the game proper kicks off as Wes decides to take down a second criminal cartel in a row for giggles because that's just how he rolls, all of that entirely with "borrowed" Pokemon he snatches from other trainers as the game has zero wild encounters.
E for Everyone BTW, nobody complained and the story/characters are still one of the better in the franchise(in my opinion). Anyone who tries to make excuse because this is a "kid's franchise" can go shove it, kids don't need to be pampered. As
@Atlictoal said, you can still make a game for all ages and make it fun and interesting without resorting to making another Let's Go game for literal toddlers(then again, I think that game was more made for Genwunners in mind, who are de-facto still mentally toddlers). Both Gamecube games have fun and interesting stories and characters that have their own unique flair and try what Gamefreak haven't, all while capturing the spirit of the franchise as a whole and keeping that E for Everyone rating. Nobody is asking for another Shadow The Hedgehog here, just writing that isn't made for literal babies and characters that aren't just coomer bait(or ugly, in case of SV)