I'd definitely rank this alongside Black/White/Black2/White2 for having the best story of any Pokemon game, if not better. It was a pretty big improvement from X/Y's storytelling. Compared to past games though, I'd say Sun and Moon is much more story driven, and it was done pretty well. It struck a perfect balance between striving to become the Island Champion and dealing with the evil teams rather than giving more weight to one factor compared to past titles.
The Overall Story and the Battles
Almost all of the Island Trials were pretty fun; the only one that wasn't too memorable was the final one, mainly because you're just walking through a corridor until your reach the Dragonium-Z. Most of the Totem Pokemon battles provided a decent challenge, especially Gumshoos/Alola Raticate, Wishiwashi, Vikavolt, and Mimikkyu; the Lurantis one was definitely the hardest one, but it was fun nonetheless. Only Totem Salazzle and Totem Kommo-o were super easy to deal with. As for the Kahuna battles, I found half of them easy (a.k.a. Hala and Nanu) while the other half offered a very fair challenge (Olivia and especially Hapu).
The other battles in the story were also a fair challenge. While the initial Guzma battle was easy, the following battles were a bit more difficult for me, mainly because I forgot about First Impression both times. Both Lusamine battles had that pesky Clefable and Mismagius to deal with. The Admin battles were pretty easy though (a.k.a. both Plumeria battles and the initial Faba when he only had has his Hypno). The entire Pokemon League was a huge improvement from X/Y too. The Elite Four and the final battle actually provide a good difficulty.
What also added to the difficulties of the battles is that unlike X/Y, the EXP system was improved. I was occasionally overleveled, but I was never too over leveled in the situation that happened in X/Y.
I did find the SOS Wild Battles pretty annoying though. I've heard they are the go to option for EV Training now, but I haven't tried that yet. Perhaps if they turn out to be good for that, my opinion will improve.
Team Skull may be a normal team of thugs, but they just thrive with personality that makes them really enjoyable. The Aether Foundation turned out to be the real bad guy all along just like the fans predicted, and even the game dropped some massive hints prior. Turns out they can be pretty dark, and the scene in the Aether Paradise labs and the preservation room best conveys this. I was also surprised by the plot twist that Team Skull was actually working for the Aether Foundation all along, and the reasons why were pretty interesting (namely has to do with Guzma's relationship with Lusamine).
As for the story, my favorite arc in the story has to be the Aether Foundation raid where you, Hau, and Gladion storm it to save Lillie and Cosmog. You could really sense the darkness of the Aether Foundation and the stakes raised high. My favorite scene in the whole game is the initial battle with Lusamine and the events that happen right before and right after. The preservation room is one of the most disturbing moments of any Pokemon game, and the Ultra Wormholes opening around Alola was one of the most tense moments in the series.
Characters:
This game has my favorite cast of characters. There isn't anyone to dislike. Kukui is even more active in the plot than Sycamore was, and he has a pretty likable personality. Hau is another friendly rival, but he knows how to leave a good impression; he even has some pretty memorable quotes when questioning Gladion's ideals. Plumeria was meh at first, but she became really likable during that scene with Team Skull in Poni Island. Guzma is a really hard character not to dislike. His dialogue was both hilarious and event serious at times (particularly during the Ultra Space event), and he has a tragic back story as well. Wicke was a sweetheart (especially when you learn she was a source of comfort during the times when Lusamine abused Lillie), and Faba was crafty and had the traits of a normal, likable villain (his disdain for children and his arrogance come to mind).
Even the Trial Captains and Kahunas were pretty memorable characters. With the Trial Captains, you get some pretty nice backstory to each of them. Acerola is my favorite of the 7; she's adorable both design and personality-wise, has some interesting lore (being a descendant of the Alola royal family), and the way she cares for Lillie and those preschoolers was pretty sweet. As for the Kahunas, they are fairly active in the plot. Hapu was my favorite out of the four due to her role in the plot and her backstory, while I'd rank Nanu as my second favorite (his team was easy, but I just love this guy's quotes and his smirk).
And then we get to the family: Lusamine, Gladion, and Lillie. Lusamine, I'd say you are the new most psychopathic villain in Pokemon history, or at least tied with Ghetsis. What this woman does during the plot will make you think she's really crazy, but unlike Ghetsis, she does have a tragic backstory herself where her obsession with the Ultra Beasts stemmed from her husband's disappearance while researching the Ultra Wormholes.
Though it is funny just thinking about the fact this guy was the one who initiated the events of Sun and Moon's story. I mean, he's the only character named Mohn, and he really looks someone that would be Lillie and Gladion's father (he has a similar hairstyle to Gladion and his eyes have a similar round shape that Lillie has, not to mention their eyebrows are similar). Yet, it is also tragic; this guy acts like he knows nothing about what his family has become, and that memory loss probably has to do with his Ultra Wormhole incident.
Gladion didn't appear in the plot as much as I though he would, but I thought he was a pretty well-written character. His reasons for becoming strong were pretty sweet, namely that he wanted to help Type: Null as much as he could after its years of torture in Aether Paradise. His words to Lillie at Poni Island were pretty sweet, though my favorite with him as to be the final battle against him in Mount Lanakila. His dialogue throughout it was great, and it did a great job showing how much he has learned how he should really become stronger. You also gained a really good sense of his desperation to achieve what he need to, and your second encounter with him in the Route 8 motel best conveys this when you learn from the motel lady how he ended up there in the first place. Like Lillie, he also cares about improving his mom for the better, evident with his words to Wicke following the first Lusamine battle and his letter to her that the same motel lady gives you in the post-game.
And Lillie. She deserves a section all on her own.
Lillie
N and Wally, I love you both so much, but I think I just found a new favorite character in the entire Pokemon series. Lillie was an incredibly well-written character throughout the adventure. Her character development was simply amazing from beginning to end. She starts out timid, but she later becomes a really confident and brave individual. She goes from becoming scared at confronting her mother to taking her head on like a true hero. Her conversation with Lusamine during the Ultra Space event is my favorite dialogue in the entire game because it really marks the culmination of her character development, and the words the two characters exchanged were pretty memorable.
Even her design change during the later part of the adventure was a really nice touch. Yet again, it demonstrates her character development. Her hat she wore previously represented Lillie's timid nature. We find out through in-game dialogue that Lusamine was such a terribly controlling mother that forced her own daughter to dress up like UB-01 because she was that obsessed with the Ultra Beasts. When Lillie wears the that hat, we see her being timid, and it's even reflected with her initial confrontation with her mother. It's almost as if when she wears the hat and lets her hairstyle resemble Nihilego's, she lets her fear of her own mother get the best of her. However, once she takes off the hat and gets a new makeover, Lillie becomes a more confident individual. By removing the hat and wearing a new style, it's almost as if she's finally releasing the oppression and fear her mother placed onto her! I've got to give it to GameFreak for doing a really great job creating such symbolism. It's for that reason that I adore Lillie's new design.
And that's not the only symbolism that portrays Lillie's character development. One of my favorite scenes in the entire game was the one where Lillie and the player character were hiding underneath a rock in Exeggutor Island while it was raining; there, Lillie recalls a time when Lusamine was a kind mother when she went out outside with her daughter while it was raining and let her sleep together for the night. it's clear that this event shaped Lillie as a character, and it demonstrated how she still has hope in changing her mother to who she once was. The weather symbolism during this scene was another great touch. The rain kicked in when Lillie was telling the player character that specific story, and then a rainbow emerged afterward. I think the rain represents Lillie's struggles throughout the years just like how rain can represent turmoil, while the rainbow symbolizes new life for Lillie; that is, she takes on a new character where she becomes a strong-minded individual. Lillie's words about that time when Lusamine cared for her and her warm words she gave to the player character provided comfort and reassurance to herself, and water can sometimes represent comfort, so the rain even symbolizes comfort.
I also really like the foreshadowing to Lillie and Lusamine's relationship, particularly during the scenes when Lillie first meets the player's mother and what she says about Professor Burnet. With the player's mother, this is what Lillie tells the player after her brief conversation with their mother.
Lillie speaks as if she's longing for a happy relationship with a mother of her own. Her dialogue with the player's mother is also worth noting. The player's mom refers to Lillie as "a very cute" friend. Lillie then states,
"Why... why thank you" as her face turns into the happy-kind of embarrassment. Later in the game, we find out Lusamine considers Lillie to be "ugly," and considering how she forced her own daughter to dress up with that fashion-style to resemble UB-01, I think we can infer that one of the ways Lusamine abused Lillie throughout all these years was that she constantly reminded her daughter that she didn't look pretty at all when she already did, so Lillie started to gain the sense she really was ugly. For someone to call her "very cute" meant a lot for her. She reacts with surprise because she's not used to others calling her that, especially when her mother thought she was "ugly", hence why her face lights up with those hints of shock and embarrassment. Yet, she also smiles because she meets a mother who is not only a kind person and the direct opposite of her own mother, but also someone who actually thinks Lillie looks cute.
The other great foreshadowing to Lillie and Lusamine's true relationship was what she says about Professor Burnet during the scene when the player visits the research lab in Heahea City:
Again, Lillie speaks this line as if she has found someone who is a real mother figure for her. The timidness in that sentence conveys her sadness over what her actual mother has become and how she wishes she was back to the way she was prior to Mohn's, a.k.a. her's dad's, disappearance. It's also worth noting Burnet is another opposite to Lusamine: a kind and caring mother in contrast to manipulative and abusive one that the latter is. You can even tell how much of a good mother figure Burnet has been throughout all of this when you read Lillie's diary in the postgame to learn the more about how the two first met.
Even Lusamine's initial encounter has some great foreshadowing for what was to come.
What triggers her to say is that when Hau mentions Lillie's name, and that line foreshadows the reveal regarding the kind of mother Lusamine is.
It's even worth mentioning how Lillie and Lusamine have some nice parallels going, and that was best explained by Plumeria:
"You know... deep down, you're kind of like the president. You've gone in a different direction, but I can tell you have the same strength in your convictions."
Getting back on track, Lillie is without a doubt my favorite character not just in Sun and Moon, but in all of Pokemon as well. Her character development is truly admirable, not to mention she's a true cinnamon roll. Her growth throughout the adventure only adds to the feels with her departure at the end of the game.
Postgame and other details:
I have only just started it, but one thing that already makes me really happy to see is the return of a large-postgame area to explore similar to the island in D/P/P, Kanto in the Johto games, eastern Unova in B/W, and southeastern Unova in B2/W2. For Sun and Moon, it looks the large-postgame area this time around is the other half of Poni Island that leads to the Battle Tree. I'm about to do the UB Task Force missions, and from what I've seen so far, they look pretty driven, so I have hope they'll deliver.
As for the other details, the soundtrack turned out to be pretty good. There are very few tracks that I dislike. The initial Lusamine battle theme is my favorite track in the game, though I also enjoyed tracks such as the Guzma theme (both encounter and battle), Team Skull's theme (both encounter and battle), the Island Kahuna theme (both encounter and battle), the trainer battle theme, the Aether Paradise theme, all the Route tracks, Ten Carat Hill, Mahalo Trail's theme, Poni Canyon's theme, Konikoni City's theme (both day and night), the Tapu Battle theme, the Elite Four theme, the League Title Defense theme, and so much more.
Even the region was pretty thrilling to explore. So many memorable locations to visit. I'd say Alola has the potential to dethrone Sinnoh for my favorite region of any Pokemon game.
Flaws:
There really isn't much that I can think of the top of my mind. I already mentioned that I found SOS Battles to be rather annoying at times. I haven't delved too much into Hyper Training and EV Training yet, but from what I've heard so far, it seems like they were a downgrade compared to generation 6.
As for the story, while Lusamine had some great moments in wherever she appeared, I think she could've appeared more frequently in the plot. I think the first visit to Aether Paradise should've happened after completing all the quests in Melemele Island, as well as encountering the Aether Foundation very early in our adventure. The second Lusamine encounter would be another visit to Aether Paradise after completing Akala Island; there, that's when I would bring UB-01 into the mix. It would give some larger space between her initial appearance as a caring woman and the foreshadowing of her true nature.
Even Guzma and Plumeria could've benefitted from a bit more story presence. I'd make the first battle with Plumeria take place as you approach Iki Town for the battle with Hala, while the first Guzma could've taken place some point near the end of Akala Island.
Other flaw: I wish you could catch the Ralts evolution family in S/M. Gardevoir would've been perfect for Lusamine, while Gallade would be a fantastic Pokemon for Gladion.
Overall:
An excellent game during the main adventure with a really good story and a memorable region. Definitely worth playing through again. We'll see how the postgame goes to determine where I'd rank this in my favorite generations list.