I personally always liked XY. I love the Pokemon of gen 6, the roller blades, the cute chibi 3d and the mega evolution mechanic, and like the spirit of Kalos as this busy, glamorous Parisian region. The main story is just short, so I was sad to see it end so soon, and could have used some more post game activities to do, though I liked the story with Emma and Looker as a starting off point.
If were to make a third game version I would increase the encounters with Diantha during the main story, because she was a character we never really got to know, despite being champion, and seeming like a nice girl.
As an actress perhaps Diantha's in production of a movie that foreshadows some of the events of the plot? She could be starring in an epic historical drama about the great war that took place in Kalos thousands of years ago, and you run into her shooting scenes from the film at different locations, and get to know her better while also learning more about the history of the region in the process.
I think they could have done something more with Diantha's Gardevoir too. Since she had a mega Gardevoir and there's text alluding to how mega evolution is linked to the bonds you have with your Pokemon then it could be nice to make her Gardevoir a more defining part of who she is. Working with this empathetic, psychic Pokemon maybe helps Diantha be more open with her emotions on camera. The power of psychic Pokemon comes from their minds so Gardevoir could be someone who teaches Diantha to use her imagination, and picture things that may not be physically there, which is what actors have to do. Her Gardevoir could be so special that she follows Diantha in the overworld sometimes, floating around outside her pokeball. In fact, why not make this a mechanic of the game in general? The player could unlock Pokemon following you once you have unlocked their ultimate potential/aka mega evolution. I would love to see this implemented for all pokémon, but if they couldn't include walking 3d overworld models with unique animations interactions for all 721 Pokemon on the 3ds, I think having special interactions for at least the pokemon that can mega evolve would be feasible. Let Diantha also give you special props from the sets of her movies that are used to decorate in poke amie and your room at home, as well as gift you movie costumes for customizing your trainer that you can't get in the clothing stores + outfits for your Pokemon that could be used in or videos if you want.
I would have given Zygarde some importance in the storyline. I personally think it's the coolest of the aura trio, and deserved a promotion from just being a Pokemon you unlock and catch post game in a dungeon, to having it's own story the way it did in the anime or like they did with Kyurem in BW2. The theme of Zygarde is that it's a guardian who is observing the ecosystem from deep within it's cave, and emerges as a protector who reveals it's true form and hidden powers if Kalos' ecosystem falls into disarray, so that's Zygarde's cue. Xerneas and Yvetal would be in the game too, and the plots of Y and X can be somewhat combined, with Lysandre going to use both of these guys, Yvetal to wipe out most of the world population, and Xerneas to bestow immortality and make gods out of the few he thinks are deserving of it, and build the beautiful new world he seeks. He didn't account for Zygarde though, and failed to realize the importance of this pokemon as a sustaining force, and hope remains while it endures.
I thought AZ's backstory itself was actually pretty good I would have kept his cut scene and dialogue about when he was king the same, but instead of just showing him as a captive, I would have had him do more to actively resist Team Flare, he refuses to tell them how to use his ultimate weapon as they literally twist his arms, in my game they would have AZ chained up, threaten to hurt his Pokemon. Let him be this once cynical person who at this final juncture of his life is not just remorseful a very brave hero. Helping AZ burst out of jail would be a longer dungeon episode that requires you to batttle numerous trainers together, let him ultimately do something self-sacrificing hold off a couple of admins with a Pokemon battle to block them from following you, giving you the time you need to find Yvetal, so Team Flare can't use his energy to power the ultimate weapon. Perhaps AZ even suffers a mortal injury, jumping in front of an attack Lysandre launches from Yvetal that was meant for you, which petrifies him to stone, or is slowly poisoning him.
Since AZ's story is one of redemption being ready to die himself to try make things right is the ultimate act of atonement he can make for the genocides he committed as a king. AZ collpasing and the direness of the situation could be the event that triggers Zygarde to go beserk and realize his complete form. Can't get too dark in a Pokemon game, so AZ could later on be healed from death's door by Xerneas healjng his wounds, and an unexpected to side effect of the presence of Zygarde the preserver, Xerneas the creator and Yvetal the destroyer all being together at once free AZ from the curse of immortality, from there he could live a normal life and age like any other human, it would echo the message that nobody is supposed to leave forever.
I would also make AZ a formidable Pokemon trainer, changing the battle with him during the parade before the credits to a challenging one that surpasses the champion and elite four, and make him the real final boss. Since he was a visionary king who fought in wars and had more than 3,000 years of experience behind him I think it makes sense for his team to be strong and high-levelled because he's lived so long. I think that scene of Floette's return would really feel even more like you had accomplished something together after a grueling battle.
I think making AZ a savage trainer would also give you something to do post game, as a secret boss that you can rematch with a Red-esque Team, including a battle with the special Floette who can use the light of ruin move. At the end of his life when he passes away he will bequeath you his Floette to watch over.
On a less serious note it would have also been fun to also introduce another eveelution in pokemon Z so that Sylveon forms a duo with either a dragon or steel Pokemon, probably steel because this is region that is inspired by a region that has kings, barons, dukes and castles, I like the idea of an armored Eevee like a knight. This Eevee would be the form that Callum/Serena evolves their Eevee into instead of Jolteon, Vaporeon or Flareon, and it would serve as the opposite of Shauna's Sylveon.
