Story:
They did very well with meshing concepts like interdimensional travel with invasive species, and, the overarching concept of life. USUM was a little generic with its story, though we finally got some of Necrozma's backstory, which deals with the idea of over-cultivation of resources due to greed through Necrozma's loss of light-making powers.
The story in both games, when examined closely, were pretty good. SuMo had a really nice mysterious vibe surrounding the Ultra Beasts and Lusamine's plan with Nebby. USUM definitely felt like going through SuMo again, but because of the inclusion of the Ultra Recon Squad, they manage to change the course of the story because of their otherworldly expertise and helped to relate more to the player because there wasn't a need for the reintroduce old UBs. It was a smart choice for the story. I like how they managed to change Lusamine from the psycho that she was in the vanillas to an over-achieving antagonist who had the best of intentions and wanted to prove that she was capable of moving on without Mohn.
For how cinematic these games were, I would have liked to see the dynamic of the Lusamine's family expanded upon a little more, to show the struggles they went through. More of a classic case of SHOW, DON'T TELL; you can't hear emotion from a line of text, like from Gladion's remark in SuMo during the Pokemon League afterparty.
The scene after the main climactic battle in SuMo with Lusamine and Lillie is the most striking and poignant piece of dialogue this series has had to offer.
The Exeggcutor Island scene in SuMo was very emotionally impactful, however, USUM's main character definitely got the short end of the stick with the Magikarp boat guy.
I'm going to aknowledge the handholding but not going to go over , it's been said over a thousand times, let's move on.
Features & Mechanics:
Pokefinder:
The Pokefinder was a nice inclusion. You take pictures of Pokemon around scenic routes, kind of like a what a real tourist would do in Hawaii. However, needing 1,500,000 thumbs-up is REALLY excessive for a 5th upgrade. It's nice to take pictures of them in their "natural habitat", but you'll have likely taken really good pictures of rare pokemon by then, essentially nullifying the feature. At least you get a stamp for completing it.
EDIT: From what I get, it's those rare pokemon that look away or make it really hard to take a good picture. There's that.
Alola Photo Club:
Alola Photo Club has got to be my favourite out of all the features in USUM besides the Battle Tree. I'm kind of a sucker for photography or art, and if I can take pictures of my Sinnohian mythicals in a super-imposed remaster of Spear Pillar or Unovan pokemon in front of a remastered Sky Arrow Bridge. COUNT ME IN. The Photo Club is beyond amazing, but the only things I don't entirely like about the Photo Club are:
1. That the camera angles aren't totally free, you can't face it upwards for more dynamic angles in areas that would have very dynamic backgrounds. (Motion-wise, kind of like the Pokedex.)
2. The inability to move your main character when you and your pokemon are doing a photo shoot.
3. The distance that your pokemon has to be away from you to perform certain actions (also stemming from point 2) and the lack of control over said actions; they could at least use the button to switch through the animations and then loop said animations. (Like the Pokedex!)
I get that Zeraora does have a really wide animation with its somersaulting kick or whatever, but do I really have to move him to the other side of the room to get him to perform it, and on point 2, do I have to wait for Black Kyurem to decide to do a "flying arm swing" instead of an "arm thrust", and then realize that it was actually performing the latter. Make it intuitive, Game Freak!
(I would have included the selection of character animations being composed of just a simple Alolan wave and Z-move animations, but due to the hardware limitations and dynamic movements of the Z-moves (which are amazingly expressive), they gets a pass.)
Battle Royales:
Battle Royales were the most interesting addition to the styles of battles. Must have been nice for the people who wanted that style, but I really do want Triple and Rotation battles back. The AI goes from its tutorial difficulty all the way to Pro, items and all, right on the first difficulty setting. Not even the battle facilities in Johto or Sinnoh had a difficulty spike that steep. Most of the time they all gang up on you. I finally got into it after a few losses with my own pokemon, but it was still pretty discouraging to play at first.
Battle Tree:
The Battle Tree is actually pretty fun, you get to battle trainers from previous generations, besides Generation 2, of course.
(This iteration of Red's team was introduced in Generation 2, but it's a bit of a stretch.)
My only minute problem with it: You don't unlock the songs played during special trainer battles (i.e. Wally, Grimsley, Cynthia) to play while battling other trainers, but at the end of the day they're special trainer themes.
Battle Agency:
It's pretty good, almost like a revamped Battle Factory, but it requires 2 other online players to have already initiated a battle in the Battle Agency for you to put them on your team. You have to deal with finding partners who are also going up the ranks around the same level as you and finally, the special boss character should have been set to only be battled at Rank 50. (It's a surprise for you guys who haven't put time into it.)
Festival Plaza:
Like Join Avenue from Black 2 and White 2, but... with a much more butchered execution. It's trying to be the PSS and Join Avenue at the same time, which causes some problems, namely: It wants to be real-time, but the game can only handle so many models and names at the same time. The way the listing system works make everything very tedious to scroll through.
The worst part about it is when you're trying to VIP someone, but the game says that you can't VIP them; from what I gather, this is likely caused because they were previously loaded up from the last session and haven't been replaced by a new round of random players.
(Still not entirely sure how it works, I'll look into everything.)
Pokemon:
Wild held items and wild Alolan pokemon:
I've tried to evolve Gligar, but I need a Razor Fang to do that. Guess what pokemon is the only pokemon to holds that item... Bruxish. Which only has a 5% encounter rate with normal fishing or 20% on "bubble" fishing (where it still barely shows up) and has a 5% chance for a Razor Fang. Unfortunately, Razor Fangs aren't obtainable in the regional battle facility like they were last generation, it's a 5% encounter item on a pokemon that appears infrequently.
Game Freak didn't even give some of the new Alolan pokemon a chance, either; most Alolan pokemon are pretty weak and the one's from the later Dex's were put have or are under 5% encounter rates in the areas that they appear in. (e.g. Passimian, Oranguru, Comfey (in SuMo), and Mimikyu (But, Mimikyu is definitely worth it)
Mythicals:
The mythicals were poorly handled in the Alola games, just like with the Kalos mythicals. They're just "Moviemons", and are just there to look pretty, sell merchandise, and add to your collection of legendary pokemon. I didn't care about Magearna until a month ago when I used it.
The Pokemon movies are usually so-so and don't give much backstory or significance about the Pokemon, which makes the mythicals suffer a lot. (Especially for the ones without backstories.) Magearna/Volcanion's movie, Volcanion and the Mechanical Wonder was very non-sensical: A mad scientist wants to destroy a meadow with a H U G E death laser for what reason now, and somehow the pokemon of the meadow produce an energy shield made of *surprise* energy, love and the ✧・゚: *✧・゚:・゚♡*power of friendship*♡:・゚✧*:・゚✧.
GF needs to up their game on the mythicals, because they're a little more special when they have some depth and significance to its region.
Yeah, Zeraora might have inspiration from Kanehekili; god of Thunder; but if so, what role does it play in the region compared to the Tapus and boxart legendaries andwhat makes it MYTHical?
Finally, the removal of the national dex:
This was such A MAJOR STEP BACKWARDS, Pokemon's catchphrase is "Gotta catch 'em all". There's not even a stupid certificate or reward for catching all 808, no incentive at all. The joy with dex's was scrolling up and down your Pokedex and checking out all of the cool formes and shinies that you've seen. Now, the Alolan national dex is behind a yearly-paid subscription service with half of the features and appeal of the in-game ones. The megas that didn't appear on the Alolan Dex don't have own entries, and the ones that do have them show up in Sun/Moon or USUM's Pokedex. Evolving an Axew or Piplup doesn't amount to anything , because they aren't in the Alola Pokedex and would've already been registered on Pokemon Bank through Gen 6.
Miscellaneous:
If anybody remembers the ORAS interview where they stated that they didn't add a battle tower because "everybody would be more interested with smartphone games instead of putting time and attention into competing in the battle facility", something upon those lines.
The series may be catered toward a younger demographic, but cutting out half of the pokedex and most of the core features just isn't the way to go.
Game Freak keeps forgetting that there are adults and older fans that still play these games, they need to stop cutting corners where they shouldn't be cut. They should have focused on making their newer games have as much content as possible, like they said when they worked on HGSS, even if that takes an extra year. Although the expositional post-game events like the Delta Episode are nice, they are just sparkly one-time events with assets that only get used once; something like the Battle Tower/Battle Frontier have replay value. I feel that Alola did have very interesting and fun gameplay; but at a few points it felt rushed and incomplete, likely because a third version for Kalos was in production, but then they decided to put effort into Alola for the 20th anniversary, because sparkly new region for big sparkly anniversary year.
They've got the money! Pokemon actually makes 1.5B annually; which means that they have more than enough to make a properly thought-out and well-executed game, no matter how long they have to wait. (The whole franchise has also grossed about $90 billion and is the all-time highest-grossing franchise, let that sink in.)
The thing that has made the Alolan games really fleshed-out and fuller, for me, is... the anime. If your supplementary media for your games feels more fleshed out than your games, you're doing it wrong. Especially when it's been shown that it can be done in previous entries.
The first visit to the Aether Paradise always felt really weird to me. Lusamine owns the place, has dozens of employees who will make sure that the island is on lock-down, and decides to not take Cosmog from Lillie for what reason? Lillie literally stole it, and then she also disowns her child in front of the player later in the story; it makes no sense!
Third-version split:
I don't think that the "third version-split" thing with USUM isn't so bad, it came around because of a design choice from the first games, namely the Sun and Moon motif, mechanics, and what not; and then they also wanted to accommodate a game for the third legendary in the trio but didn't want to do a sequel, so it ended up being a split third version. It does nullify the vanilla versions to an extent, but it does offer what a standard third version would offer: New features, additional areas & content, and a story revolving around third legendary trio member.
*SuMo/USUM main character's official names are actually Elio & Selene, betcha didn't know that.