This review contains spoilers
I'm afraid I don't like Pokémon's Gen VI, moreso than any other generation I've completed (as of the time of this writing, Pokémon Moon is the last mainline game I finished). I fully acknowledge that I'm not in the target demographic anymore, since this was the first game made for the mobile generation (to which I do not belong). This game has a lot of fans from its target demographic, which is perfectly fine. But with respect to what interests me in the series, there's little to draw me in.
Part of the issue is how easy the game is, even on a challenge run (which this playthrough was, see here: https://www.youtube.com/playlist?list=PLM77nBc1XrUqO6eMf6YSvq6Eizp8NHKsn). Pokémon hasn't been difficult for me since I was a kid, and I don't ever expect it to get back there again - but even then, this game is so easy to break. By the second gym, the player has access to two starters (one Kalos, one Kanto), a fossil Pokémon, Snorlax, and Steelix, none of which require much extra effort for the player to attain. By the fourth gym, the player has additional access to Lapras and Mega Lucario, also requiring little to no effort on the player's part. You could make an argument that this is simply the game giving the player extra options, but I dunno, when all of these Pokémon are more or less given to the player, there's pressure on the game's part to use at least some of those (and indeed, on my first playthrough, I used both starters and Mega Lucario).
I also generally don't think the game's theming really comes together in the way they intended. In interviews, the creators have stated that the game is meant to emphasize the confluence of individuals, the idea of the happy fortune that we should get to be alive at the same time as the other people we get to know in our lives. This is a deliberately less complicated than the themes of duality and taoism emphasized in Gen V and is reflected in the emphasis of rivals as a friend group rather than individuals embodying ideals (compare Calem/Serena/Shauna/Tierno/Trevor with Bianca/Cheren) and a lower-stakes villain group (compare Team Flare to Team Plasma). There's nothing wrong with shooting for a lower thematic scope, but to my way of thinking, the game completely fails at that. We don't really experience Gen VI's rivals as friends on shared/parallel journeys so much as we do pestersome individuals who keep crossing our path to exposit what they've been doing and fight badly before running away for a while; I guess we come close to that with Shauna being bi-coded, but that only really matters for the very start of the adventure and was done by complete accident. Team Flare as a whole poses a substantially more serious threat than Team Plasma, despite its individual members being pushover jokes; Lysandre is presented as a fascist who believes in aesthetic purity and the preservation of the elite few in the face of a genocidal pogrom, Malva implies that this movement has invaded both news media and the regional government, and (while I admittedly haven't been interested enough to explore the post-game, as I understand it-) Xerosic proves that Flare is willing to leverage ready slave labor. This is to say nothing of the fact that Lysandre is either the series' first confirmed kill or is immortal and doomed to spend the rest of his days buried under several tons of rock and steel. There is little consistency or deliberate choice in how these actors perform their roles.
There is also a lot of fatigue with the series' established structure by this point. By Gen VI, Pokémon was still adhering to the template of Gen I, resulting in the game trying to stuff 6 generations of content into a single generation's worth of pacing. This is why we see so few new Pokémon, and why so much emphasis was placed on making older Pokémon relevant through Mega Evolutions and the addition of the Fairy type. I'm not necessarily opposed to making older Pokémon relevant again - I LOVE regional forms - but later generations feel like they put a lot more thought into pacing out how older Pokémon are reintegrated. Here... well, I mentioned how many powerful options are thrown at the player early on; this is a consequence of that. After a certain point, the sheer amount of STUFF the player gets between Pokémon and key items is more tedious than anything.
But there are things I like. I think some of the gym leaders are well-implemented; I wish Korrina were more relevant than she was, I think Valerie is a great primer on the Fairy Type and well-placed as she is in the game's narrative, the Anistar gym is a nice spectacle piece, and there's some rare self-awareness with Wulfric admitting beforehand that he might be a throwaway fight. Some clever ideas are lifted from previous generations (Clemont is Elesa by way of Blaine, the Kalos league has the same neat freeform structure as the Unova league), but it's done with solid enough intent here. There is a lot of incidental miscellaneous stuff the player can get up to, and while I myself have little time for it these days, I'm sure I would've gotten a big kick out of it as a kid (certainly, we had a lot of fun making a Trainer PR Video in the challenge run). I don't think Kalos is a great take on France, but France is such an inherently interesting country that what does filter through in places like Lumiose City and Parfum Palace still shines bright.
The one thing I think the game does unequivocably well is the character AZ. What a compelling, concisely, well-written character. He barely shows up, but the few times he does, he carries such a strange, unique presence for the series. "The man's beloved Pokémon took part in the war. Several years passed. He was given a tiny box." is immaculately evocative in a way I never would have expected the series could be capable of. And my very favorite moment, one of those thematic beats that shines brighter than almost anything in a series with generally low thematic aspirations, is that surprise fight against AZ in the credits. Yes, the fight is hardly a challenge after the fight against Diantha - but that's the point. The fight isn't about YOU and YOUR journey, it's about AZ and HIS journey, his own rehabilitation into a society from which he condemned himself. It is the singular moment around which that central theme - the confluence of souls - works. In a game of missed shots, it nailed the one moment it needed to hit more than any other. It is this one, single moment that makes the whole rest of the game worth playing.
Part of the issue is how easy the game is, even on a challenge run (which this playthrough was, see here: https://www.youtube.com/playlist?list=PLM77nBc1XrUqO6eMf6YSvq6Eizp8NHKsn). Pokémon hasn't been difficult for me since I was a kid, and I don't ever expect it to get back there again - but even then, this game is so easy to break. By the second gym, the player has access to two starters (one Kalos, one Kanto), a fossil Pokémon, Snorlax, and Steelix, none of which require much extra effort for the player to attain. By the fourth gym, the player has additional access to Lapras and Mega Lucario, also requiring little to no effort on the player's part. You could make an argument that this is simply the game giving the player extra options, but I dunno, when all of these Pokémon are more or less given to the player, there's pressure on the game's part to use at least some of those (and indeed, on my first playthrough, I used both starters and Mega Lucario).
I also generally don't think the game's theming really comes together in the way they intended. In interviews, the creators have stated that the game is meant to emphasize the confluence of individuals, the idea of the happy fortune that we should get to be alive at the same time as the other people we get to know in our lives. This is a deliberately less complicated than the themes of duality and taoism emphasized in Gen V and is reflected in the emphasis of rivals as a friend group rather than individuals embodying ideals (compare Calem/Serena/Shauna/Tierno/Trevor with Bianca/Cheren) and a lower-stakes villain group (compare Team Flare to Team Plasma). There's nothing wrong with shooting for a lower thematic scope, but to my way of thinking, the game completely fails at that. We don't really experience Gen VI's rivals as friends on shared/parallel journeys so much as we do pestersome individuals who keep crossing our path to exposit what they've been doing and fight badly before running away for a while; I guess we come close to that with Shauna being bi-coded, but that only really matters for the very start of the adventure and was done by complete accident. Team Flare as a whole poses a substantially more serious threat than Team Plasma, despite its individual members being pushover jokes; Lysandre is presented as a fascist who believes in aesthetic purity and the preservation of the elite few in the face of a genocidal pogrom, Malva implies that this movement has invaded both news media and the regional government, and (while I admittedly haven't been interested enough to explore the post-game, as I understand it-) Xerosic proves that Flare is willing to leverage ready slave labor. This is to say nothing of the fact that Lysandre is either the series' first confirmed kill or is immortal and doomed to spend the rest of his days buried under several tons of rock and steel. There is little consistency or deliberate choice in how these actors perform their roles.
There is also a lot of fatigue with the series' established structure by this point. By Gen VI, Pokémon was still adhering to the template of Gen I, resulting in the game trying to stuff 6 generations of content into a single generation's worth of pacing. This is why we see so few new Pokémon, and why so much emphasis was placed on making older Pokémon relevant through Mega Evolutions and the addition of the Fairy type. I'm not necessarily opposed to making older Pokémon relevant again - I LOVE regional forms - but later generations feel like they put a lot more thought into pacing out how older Pokémon are reintegrated. Here... well, I mentioned how many powerful options are thrown at the player early on; this is a consequence of that. After a certain point, the sheer amount of STUFF the player gets between Pokémon and key items is more tedious than anything.
But there are things I like. I think some of the gym leaders are well-implemented; I wish Korrina were more relevant than she was, I think Valerie is a great primer on the Fairy Type and well-placed as she is in the game's narrative, the Anistar gym is a nice spectacle piece, and there's some rare self-awareness with Wulfric admitting beforehand that he might be a throwaway fight. Some clever ideas are lifted from previous generations (Clemont is Elesa by way of Blaine, the Kalos league has the same neat freeform structure as the Unova league), but it's done with solid enough intent here. There is a lot of incidental miscellaneous stuff the player can get up to, and while I myself have little time for it these days, I'm sure I would've gotten a big kick out of it as a kid (certainly, we had a lot of fun making a Trainer PR Video in the challenge run). I don't think Kalos is a great take on France, but France is such an inherently interesting country that what does filter through in places like Lumiose City and Parfum Palace still shines bright.
The one thing I think the game does unequivocably well is the character AZ. What a compelling, concisely, well-written character. He barely shows up, but the few times he does, he carries such a strange, unique presence for the series. "The man's beloved Pokémon took part in the war. Several years passed. He was given a tiny box." is immaculately evocative in a way I never would have expected the series could be capable of. And my very favorite moment, one of those thematic beats that shines brighter than almost anything in a series with generally low thematic aspirations, is that surprise fight against AZ in the credits. Yes, the fight is hardly a challenge after the fight against Diantha - but that's the point. The fight isn't about YOU and YOUR journey, it's about AZ and HIS journey, his own rehabilitation into a society from which he condemned himself. It is the singular moment around which that central theme - the confluence of souls - works. In a game of missed shots, it nailed the one moment it needed to hit more than any other. It is this one, single moment that makes the whole rest of the game worth playing.