Less Pokémon being caught was for the better, as before it just led to many of them getting the shaft. I also was fine with Ash only using Kalos Pokémon for the league. The league was better than BW, but Ash deserved to win (runner-up is still great progress) and while I'm fine with some minor battles getting glossed over, they cut a bit too much and it led to stuff like Mega Charizard X vs. Y being a complete joke.
The rivals are fine (assuming they eventually let Ash beat Alain in a battle). I feel like Sawyer should've been introduced earlier on though, and Trevor didn't get enough appearances. I liked the Showcase arc, but it basically left Serena with nothing to do after it (even before it, she had to search for her purpose). Same with Clemont; he basically had nothing left but his gimmick after the Gym Battle. Bonnie, on the other hand, didn't get much of the spotlight before XYZ, but now Squishy makes her a pretty major character. So I guess poor character focus balancing is my biggest disappointment.
1. The endings.
2. Lack of continuity with previous series.
3. Squishy being terribly underused and underdeveloped.
4. Team Flare not getting any encounters with the twerps in a whole semester.
5. The lack of rivals and recourring characters in the first 50 episodes.
6. The league.
7. The lack of risks taken in the first 50 episodes.
8. Bonnie not having a goal or a story for herself.
Other things sucked too (Serena, Ash's team planning, etc...) but I didn't had much hopes for them or didn't care. The lack of a ORAS arc also disappointed me at the moment but nowadays it's not that bad.
The Pokémon Showcases disappointed me the most, no doubt about it. Not that I was expecting great things from them, I knew they were going to be shitty tournaments from the moment Shauna explained to Serena what they were. However, even knowing they wouldn't be any good, I have to vote for them as they are the biggest reason why I don't find the XY series to be as good as most of the fandom seems to think (something which is changing now that we are approaching the series finale and people are pissed off with the League results).
In my opinion, all the fans disappointed with the League can only blame themselves. Hype is created by fans, after all. The network was showing teasers for the League episodes like it shows for the unimportant episodes. The fans were the ones who got their hopes up and assumed Ash was already the winner. I'm in no way saying that you guys don't have the right to be sad about the way the League played out and how you should feel. What I'm really saying is that you should know better by now. I've learned to lower my expectations, you guys can do it too.
Ash losing the League doesn't bother me in the slightest. I am used to it. Fans are saying that the writers missed the chance to redeem Ash. Redeeming him from what exactly? The XY series has been pretty much Ash's glory saga, and being a finalist in a Pokémon League Conference isn't a bad thing Ash should be ashamed of. Of all strong Trainers who competed in the Lumiose Conference, Ash is the second best. What have you guys done with your lives so far? Are you here in Brazil getting medals at the Olympics?
The League was decent, not absolutely fantastic, not tremendously bad either. There are worse things, like how Serena was completely useless until she entered her first Showcase in XY060: A Showcase Debut! and started a quest so poorly written and short lived (it ended 53 episodes after it started, in XY113: Performing a Pathway to the Future!) that it took Serena more episodes to discover what her dream was than actually chasing that dream. Ash had a good run. Serena's whole journey makes you question what the writers were even thinking.
The most disappointing thing of XY, imo, is that Alain, Saywer, Bonnie and Mairin weren't the stars of the saga. They were some of my favorite characters of the entire series and they deserved more coverage.
Jokes aside, it's a tie between the writing around Ash during the saga, or the horrid pacing. The first half of the series was so slow and dull, and then they kick it into high gear and rush everything? The show has good ideas, and I think they could have been done better if they planned things out more.
Serena. While there were highlights, her overall development and goal were poorly handled. And to that extent, Showcases.
Then Goodra's sub-par performance in the League. Its one of my favorite Pokemon but didn't manage to get a solid win despite being theoretically the strongest Pokemon on Ash's Kalos team aside from Greninja.
And Alain's apparent invincibility also wore out its welcome. His Charizard took way too many hits to not have gone down in the finals.
1. Ash losing the league despite the huge build up that gave an inkling that he could win
2. Lack of diversity on Ash's team. 3 flying types, 2 dragons. I blame this though on the small amount of Pokemon introduced this generation.
3. Ash not getting a traditional mega. Charizard or Sceptile could have easily been his mega (or Heracross or another one of his mon that I am forgetting). The Ash-Greninja thing is a nice concept, but that I feel is more of a prelude to Generation 7 than a Mega from Gen 6.
4. Serena could have had more development. She's my favorite female traveling companion for Ash aside from Dawn, who in all irony I think had the best character development of Ash's female traveling companions.
5. Sawyer was just flat out annoying.
6. The writers taking so long introducing Alain into the main series.
7. Team Rocket (as much as I wish they would go away) not having more Pokemon on their teams
8. The length of time it took from Ash's seventh badge win to his badge with with Wulfric
9. Goodra, despite being annoying to me, should have just stayed on Ash's team.
10. Noivern not getting more development
11. Hawluchu not getting more development
12. Froakie taking so long to evolve to Frogadier/Greninja.
Overall XY was a very good series, probably more enjoyable for me than the original series, advanced generation, and black and white.
I was disappointed with the League for allowing Ash to lose in the end despite all the hype that was created and the hints that were given beforehand, but I got over that pretty fast.
Alain was pretty OP with his MegaZard, and Sawyer seemed to progress way too fast, especially finding a keystone and a mega stone to mega evolve Sceptile with. Ash's rivals didn't get much spotlight, and his traveling companions had poor development throughout most of the series. Serena's Kalos Queen goals were mishandled, starting very late, progressing too fast, and ending a little too quickly. Clemont didn't get many episodes to himself, and I wish he had his Heliolisk with him. Bonnie's never mentioned her goals after becoming a trainer, but she's still a child.
The thing that irked me the most was how Team Rocket was portrayed throughout most of the series. Even back to the old selves, they are still annoying and are not even least bit funny. And it was even more annoying with them appearing in episodes that didn't require them nor advanced the plot in a proper manner. Not to mention the fact that they didn't capture more Pokemon like they did in previous series. And being totally incompetent at times against certain characters didn't get my positive attention.
I have no qualms about Alain winning the league, I just don't appreciate the hype and the suggestive hints from the writers that Ash was maybe going to be the winner. They should have just focused the promotion on the team flare arc and just let the league be whatever it was meant to be.
For me it was between the League being used as a subplot for the Team Flare Arc and the lack of past references. Since the past wasn't directly stated I ultimately voted for lack of reserves. If Ash was going to win a league, I figured it should be a true team effort of all of Ash's experience, vs keeping it to a single regions worth. But about this league, it started off on the wrong foot by trying to focus on something not Ash related and yet it still flashed in and out of that battle, which was heavily one sided from the get-go. It's not like we hadn't know Alain was some amazingly powerful trainer. Anyway the fact Ash only got one onscreen win that wasn't chopped up is pretty lackluster
I never had any real problem with Alain, in fact I like the change from our typical protagonist. Was his Charizard ridiculous, heck yeah he was, but hey, Charizard is what Pikachu is to Ash.
I picked "other" for a very unorthodox reason: the original Japanese version of it.
Reason being that this saga was where I decided I'd follow it in Japanese as well as the dub. So, basically, even though the first movie was the first Pokemon thing I experienced in Japanese, this saga was my first major exposure to the Japanese show itself. And more than a year after the fact, I'm still regretting giving it the time of day. Though many of my problems with the JP version apply to all sagas, this saga was where I discovered those problems for the first time, hence why I'm singling it out here. Just refer to that "what don't you like about the Japanese version" thread I started (or any of my posts in the "unpopular opinions on the [cartoon]" thread) if you want to know my reasons why I returned to the dub in a hurry.