It'd be a perfect opportunity to cameo previous movie antagonists, and in the end credits for Pokemon Heroes Annie and Oakley read about Lawrence III (from the second movie) in the prison library so there is precedent. Some movie characters like Butler and Kidd realised the folly of their intentions in seeking out Groudon and Mew, they'd be able to warn Go about going too far. Butler nearly lost Diane because of his focus on creating Groudon, like how Go's goal of catching every type of Pokemon has been a sore point for Raboot.What if Go stumbles upon a book which contains stories highly similar to trainers who went to extreme lengths to capture legendary Pokemon and failed due to unethical methods? (I’m thinking including the movie stories too). I’m not saying anything good/bad about Go here, but it would be nice if he ended up with some introspection on the actual implications of capturing Mew and exactly how capturing all Pokémon will get him closer to the goal.