Now we come to Ula'ula Island, the largest of the Alolan islands and where the story started to ramp up.
Books are pretty great and Acerola seems to think so too. You can find her chilling in the Malie City Library, at the north-west corner of the ground floor. Speak to her and she'll present a riddle based on four book titles. Your only clue is the first book title: "Springing Forth from Alola".
In which case, the books you need to choose are, in this order: "Some Myriad Z-Move Notes", "Falling In with the Seafolk" and "When Terrific Tapu Travel". If you haven't sussed it out already, the four books begin with "Spring", "Summer", "Fall" and "Winter". If you use your imagination a little!
Your reward for solving the riddle is insight into the Legendary Pokémon.
Haina Desert is a pretty mysterious place, but one mystery remains unsolved. If you return to the desert, you can find a strange man in the empty area that you can reach by exiting north and then east from the entrance. Show him a Solrock (Ultra Sun) or Lunatone (Ultra Moon) and you'll receive a Sun Stone or Moon Stone respectively.
If you recall, Tapu Village wasn't always a bunch of ruins--apparently it was destroyed by Tapu Bulu long ago. However nobody really knows the truth. A reporter researching this incident can be found just outside the abandoned Thrifty Megamart on Route 14. Bring Tapu Bulu to her and you can go back home with a Grassy Seed .
After completing Episode RR, two Aether Foundation employees will show up inside the Aether House on Route 15. Specifically in the room on the right. The employee in the helmet will offer you a rare Porygon , while the woman gives you an Up-Grade to evolve it. However you're missing its final evolution item.
Zygarde, the Kalos region's third Legendary Pokémon, resides at the end of Resolution Cave on Poni Island. If you caught it, you should pay a visit to the Aether Foundation trailer at Route 16, east from the Pokémon Center. Inside, you'll meet Sina and Dexio again. They'll offer to unlock Zygarde's true power for you, but only after testing you.
Pokémon Trainer Dexio
The Alolan Raichu is also a speedy special attacker, but has slightly lower damage output than Espeon. It can use Psychic and Thunderbolt for STAB, and Light Screen and Reflect to bolster its party's defenses. Ground or Dark-types are strongly recommended; Bugs and Ghosts should also do the trick.
Slowking is a slow-moving, but bulky special attacker. It can use Psychic for STAB, and forgoes Water-type STAB for Power Gem, Flamethrower and Ice Beam. Dark-types are recommended; Electric and Ghost-types are also solid choices. Grass and Bug-types are super-effective, but weak to Slowking's coverage moves.
Alakazam is fast and hits hard with its special attacks, but incredibly frail. Since Dexio gave you his Alakazite, his Alakazam won't Mega Evolve. It has Psychic and Psyshock for STAB (each targeting a different defense), and Focus Blast to handle Steel and Dark-types. Ghosts are ideal, but they should have full fealth.
Finally, Dexio wants to show off his Zygarde 10% Forme. This dog-like variant of Zygarde has great Attack and Speed, but poor bulk. For attacks, it has Dragon Pulse and Earthquake for STAB, Crunch to hurt Ghosts etc., and Camouflage to become a Normal-type inside the building. Ice-types are its bane; Fairies are great too.
Pass the test and you'll receive Dexio's Zygarde 10% Forme and a Zygarde Cube containing 40 Zygarde Cells . Now you've got all the tools to make the ultimate Zygarde! To do so, inspect the Reassembly Unit towards the right. Make sure you have the Zygarde from Resolution Cave with you.
Not including the instructions, two options will be available: Assembly and Separation. The first option--Assembly--lets you build a Zygarde using the Zygarde Cells currently in the Zygarde Cube. Meanwhile the second--Separation--lets you break up a Zygarde into its constituent Zygarde Cells, and transfer them to the Zygarde Cube.
To proper understand everything, you need to know there are exactly three Zygarde forms, each comprising of a specific amount of Zygarde Cells. First you have Zygarde 10% Forme , which is the dog; this form is built from 10 Zygarde Cells, hence the 10%. This is obviously the weakest form, but still useful because it's the fastest one.
Next, you have Zygarde 50% Forme , which is the serpent--and also the "original" Zygarde introduced in Pokémon X and Y. This Zygarde is built from, you guessed it, 50 Zygarde Cells. In this guise, Zygarde is roughly at half power. Finally, there's Zygarde Complete Forme , which resembles a humanoid... or a mecha, if you prefer.
This final form is built from 100 Zygarde Cells and is Zygarde's true, ultimate form. However there's a slight complication: Zygarde Complete Forme is a temporary form, not a permanent one. Instead, what you normally have is a Zygarde 10% Forme or a Zygarde 50% Forme that has the Power Construct Ability.
During battle, a Zygarde with the Power Construct Ability automatically transforms into its Complete Forme after going below half HP. This means you have to start off with the weaker Zygarde and hope that the foe lowers your HP just the right amount. But if it works, it's worth it since Zygarde Complete Forme is pretty hard to defeat.
Anyway, that's how Zygarde works, but first we need to properly build it. If you haven't already noticed, the game has kindly provided exactly 100 Zygarde Cells for you to work with: 50 from the Zygarde in Resolution Cave, 10 from the Zygarde obtained from Dexio, and 40 from the Zygarde Cube.
What you need to do is find a way to properly combine these cells together. First, choose one of the Zygarde you own and select the Separation option to convert it into Zygarde Cells. Or both of them if you're not feeling particularly attached. The result that you want is a single Zygarde or no Zygarde at all.
Next, choose the Assembly option. If you kept a Zygarde, choose "Using Zygarde and the Zygarde Cube". Then choose the Zygarde. If you did it right, your chosen Zygarde will gain the Power Construct Ability. Or if you separated both Zygarde, choose "Using the Zygarde Cube only" to generate a brand new Zygarde with Power Construct.
Last but not least, the Zygarde Cube has two additional functions. If you use it from your bag, you can teach various moves to any of your Zygarde, including its three signature moves (because one isn't enough). Also, if you have a Zygarde with Power Construct, you can switch between its 10% and 50% forms.
No Going Back!
As the game makes it clear, separating a Zygarde into its cells will cause the Zygarde to be lost forever , so make sure you know what you're doing! What the game doesn't tell you is that once a Zygarde has Power Construct, the reverse situation occurs--it cannot be separated. Again, choose wisely.
Starting with Nanu
When you started off on your journey, you received a starter Pokémon from Melemele's island kahuna, Hala. However have you ever wondered how Pokémon trainers on other islands get started? If so, go and visit the police station on Route 17. There, you can help a young trainer choose their starter from Nanu.
Team Skull Fashion
For all their tough talk and flamboyant posing, at the end of the day, it's hard to truly detest the goofy Team Skull Grunts. If you're a fan of Team Skull and would love to have a bit of Team Skull flair to your life, check out the Pokémon Center in Po Town. The grunts there will let you buy a Team Skull Tank and Cap for 10,000 Poké Dollars.
Rising to the Challenge
Dotted around Alola are various "boss" trainers, who you can only fight after you've defeated all the other trainers in the route. Taking it one step further, there's a trainer near the Mount Lanakila Pokémon Center, who you can only fight after defeating all the boss trainers. So effectively the... boss, boss trainer?
Anyhow, if you're missing some trainers to defeat, just ask him for their general location.
Torkoal has a Heat Rock that lengthens the duration of sunny weather, which it can trigger with Drought when it's sent into battle. For attacks, it can use Fire Blast, which receives a power boost from the sun, and Solar Beam to hurt Water, Ground and Rock-types (skipping the charging turn during the sun). If possible, cancel its weather with your own or Cloud Nine etc.
Likewise, Pelipper has a Damp Rock that increases the duration of rain, which it will trigger with Drizzle as soon as it enters battle. It can use Hydro Pump, which is boosted thanks to the rain, and Hurricane, which has 100% accuracy in the rain. Electric-types are its bane, especially since Pelipper isn't known for being fast, like most Electric-types.
Meanwhile his Alolan Ninetales has an Icy Rock that extends the duration of hail, triggered by its Snow Warning Ability. Attack-wise, it can use Blizzard, which has perfect accuracy when there's hail, and Dazzling Gleam. Thankfully, hail is much less annoying than the sun or rain. Anyway, Steel-types are ideal; Fire, Rock and Poison-types are also good.
Finally, Gigalith has a Smooth Rock that makes sandstorms last longer; of course, a sandstorm will be conjured by its Sand Stream Ability. For attacks, it has Stone Edge for STAB, and Earthquake for hitting Steel-types. Like hail, sandstorm isn't too bad, but keep in mind it will boost Gigalith's Special Defense. Water or Grass-types are recommended.
After winning, you'll receive a Life Orb , which increases the Pokémon's damage output at the cost of inflicting a small amount of damage to itself. For best results, give it to a Pokémon with exceptional Attack or Special Attack. Or a Pokémon with the Unaware ability, which will passively negate the recoil damage.