Nice to read all of your replies! And thank you, Rainbow, for giving me the Thread of the Day-prefix. :)
I'll do one of my own:
What do you consider a good postgame? What are its elements?
I like a postgame that makes you wanna keep playing, improve your team and get the most out of them. Stuff like the Battle Frontier/Maison/Tree might be good for this, but the game then also is required to have something that makes training and grinding less tedious. Allow trainer and Gym Leader rematches, up the levels of all trainers and make things a lot more harder. One game does these things better than the other. Some of these facilities are also more challenging than the other.
Other things are an extended story, more areas to explore (with more challenges and some story attached), and quests for legendary or specific Pok?mon to catch. Though BW have an entire half of the map that can be explored in the postgame, there is no reason why you should. Aside from trainers and some items, you can essentially skip that entire place if you wanted. BW2 utilized the region map better to create a more interesting journey, and also added interesting stuff in different locations throughout the entire region for the postgame. That makes you wanna backtrack and keep playing the game longer.
I think it's also important to have specific events tied to the postgame, but that's not all a game can rely on after finishing the original story. While SM has the Ultra Beasts quest, there's virtually nothing else to do than the Battle Tree. That's a huge miss and I don't know why they kept the postgame so lackluster when the maingame is so extensive.
So, to sum up: new facilities, rematches with higher levels, new areas with an additional side story and multiple postgame events.
Which game(s) had, in your opinion, the best postgame?
I agree with Rainbow: all Gen IV games had amazing postgames. DP had the Areas, new Pok?mon to catch and a lot of things to do. Platinum even further improved this by creating a whole new Battle Frontier. I am not counting Kanto as the postgame but even without that HGSS have a lot to offer after you've gotten all 16 badges. I've never had the thought 'wow, I wish there was more to do' for any of these things. Even after 10 years I feel like I haven't explored every corner of Sinnoh yet - it just
feels so big.
However, my personal favourite postgame is Pok?mon Emerald. I've never experienced a facility as fun as the original Battle Frontier and it made me want to train all my Pok?mon as extensively as possible so I could even begin to try going through all the facilities. Some of them are pretty easy, some are so hard that I never got a 7-win streak.
What makes Emerald so fun to play for me over all other installments with a similar battle facility is that it's insanely easy to level your Pok?mon up. There's Match Call, with which you can rematch both regular trainers and Gym Leaders (a feature I still wish to see return up to this day!!), and there's the League that even without level-upping is at a considerable enough level to be useful for training. There's less in the game in the department of postgame events or a new storyline, but for me the Battle Frontier is so challenging enough that I keep coming back to the game to try. Even after all these years, I have the most fun here.
Which game(s) had the worst postgame and how could it have been improved?
SM has a lackluster postgame and I honestly expected more to do. On top of that, grinding has become super hard due to the returned Gen V Exp. mechanics so a lot of times I don't even
want to try making my Pok?mon stronger. Rematching the Elite Four is the most useful way, however you're considerably slowed down with the cutscenes, keeping you from grinding and grinding for hours. I am disappointed.
BW suffers from the big problem that a lot of its functionalities were tied to the WFC and now that that's gone, there's not much to do. Black City/White Forest are very nice ideas, but at this point everyone has either moved on from BW or sold their copies, so it's hard as hell to expand your city/forest. And like I said above, BW might have an entire half of the map to explore, there's no sidequest you're bound to so there's nothing to do there really. But what BW does better than SM is that its difficulty increases incredibly after beating N and that it's considerably easier to train Pok?mon due to the higher level of wild and trainer Pok?mon. Also Audino are the best thing BW could ever have. So BW has a lot of opportunities but lets down; BW2 improves this greatly.
It'd be nice though if nearly non-existent postgames were not Game Freak's usual plan for the first pair of a generation....
Why do they do this? I understand RS and
maybe BW having this problem, but XY and SM? I wonder if it's them not having any ideas for postgame or having specific motivations (like making the 'third' versions more attractive), but it takes away so much of the joy playing the game when such a good story like SM's is followed up by... Nothing really. If the UB don't interest you, there's nothing else to do because the Battle Tree isn't exactly entry-level IMO. You need to train a bit for that, and that has become very hard.