Hau'Oli Cemetary has Drifloons during the day and Misdreavus at night
Definitely worth picking up Brick Break before the trial considering what you come up against. Alolan Raticate in Moon and Yungoos in Sun.
Route 3 Berry Tree does not always guarantee a Crabrawler. This was kinda frustrating.
Seaward Cave needs access to Surf before you can get to the Grass in this area (Where Bagon is more common than on top of the cliff, and I also presume this is where Totodile spawns from Island Scan). This isn't available until Island Two.
Farthest Hollow also has Rockruff as a wild Encounter.
There's no information here about Hala's team (under Iki Town). He's a Fighting type trainer [Mankey/Makuhita/Crabrawler].
Might be an idea to "Split" the walkthrough as different Islands? Or put in a break or dashed line etc between the islands so you know where one ends and another begins.
There is an Oval Stone near the Nursery (In the small fenced off area in front of it).
Brooklet Hill has a teeny mention of Lana and the fact there is a trial there. Wishiwashi is potentially very scary at this point. The Scald TM is also located here and is definitely worth the 20 second detour to get (Second Pool, eastern side). It massively amps any water Pokemon up that you have available at that point.
Wela Volcano Park doesn't mention a Totem Trial or Kaiwe. It's also duplicated for some reason? Salazzle isn't as scary as Wishiwashi, but could potentially pose a problem due to its high speed. Kangaskhan is also available here as an ultra rare encounter (1%).
There's no mention of Lush Jungle, Meadow or her Trial either. Lurantis is a giant pain in the ass regardless of your team (you're very unlikely to OHKO). All you need to do is hunt around for a few items and the Grass Knot TM is also there. Lots of cool Pokemon in that location too.
Olivia's Store in Konikoni also sells the Fossils (Skull/Cover/Plume/Shield [I think those are the names, for Cranidos, Tirtouga, Archen and Sheildon]). Two of them are Moon and two are sun (one of each Gen 4/5).
Ruins of life is where you battle Olivia herself. She's a Rock trainer [Nosepass/Boldore/Lycanroc].
Hano Grand resort, and by extension Hano Beach (which is to the east) has some interesting things. The Beach allows you to get paid for picking up Pyukumuku repeatedly (20k a pop for a 2 minute minigame type thing). The Beach also has Staryus and Sandygasts on its northern end.
Malie Garden also has Araquanid/Poliwag and Magikarp available.
Route 11 also has Pancham as a wild Encounter. I think you've also managed to copy some info from the City into this route?
There is no mention of Mount Hokulani anywhere. Considering this is the location of Sophocles' Trial that kinda surprising. You also fight Molayne here too. Wild Pokemon in this area include Beldum, Fearow, Cleffa (night), Ditto, Minior and Skarmory.
Tapu Village/Route 14 should have the information about Captain Acerola and her Trial, as opposed to Route 15. Totem Mimikyu can be a real threat.
Route 15, Grimsley also gives you access to Sharpedo, which is basically Tauros on the water. It's also a lot of fun just zooming around all over the place. Route 14 is the location of the MegaMart, not 15.
I think you fight Nanu before you head off to the Aether Paradise again. He's got a Dark theme [Sableye, Krokorok, Alolan Persian].
Aether Paradise Round 2 is awesome and probably the most interesting part of the game. Things start coming to a head here.
Poni Island: Come on, at least name the Boats as the Pokemon they are! Huntail (I think) has a guy who gives you Magamarizer and Electarizer (To evolve Magmar/Electabuzz) [Same boat as Aerodactyl], Wailord has a place where you can get Heart Scales.
Ancient Poni Path is where Hapu lives and is also where you get the Machamp Pokeride for Strength.
Exeggutor Island has a forced Alolan Exeggutor encounter, it's also where you pick up the Sunne/Moone Flute.
Route 17 is back on Island 3, Probably worth explaining WHY you come back here and what happens next. Definitely worth talking about the summoning of the version legend and the tough fight which comes soon after.
Poni Island (Island 4), has proper names for all of its routes.
Vast Poni Canyon is also where Charjabug finally evolves into Vikavolt. You also fight newly crowned Kahuna Hapu who has a very strong team [Ground typed, Alolan Dugtrio, Gastrodon, Flygon, Mudsdale]. This area was absolute hell, it's very long and there are not many heal spots, but Lillie does her best to keep you going. You fight the Totem Kommo-O here, which is a tough fight all round. It loves spamming Clanging Scales quite a lot though.
After that, you head back to Tapu Village... And then up the mountain. You fight Gladion again, climb the mountain, fight Hau and then you head up to the Elite 4... Probably the toughest E4 for a while actually. A good mix of Pokemon and types.