SOS Chaining: Guide to Shiny Hunting in the Alola Region
SOS Chaining is widely considered the best way to shiny hunt in the Generation 7 games due to its simplicity and the range of shiny Pokémon available. This guide will go over how to shiny hunt with this method and how to optimize it to get the exact Pokémon you want.
What Is SOS Chaining?
SOS chaining is a method of shiny hunting that uses the mechanic in the Alola region called SOS battles. These occur in Totem Battles but can also happen in wild battles. In the latter scenario, a Pokémon will call for help when its health is lowered.
This will result in another Pokémon joining the battle, most commonly of the same species. In a regular battle, this can be frustrating. However, we can exploit this mechanic to our advantage.
Benefits of SOS Chaining
As the title of this guide suggests, we can use the SOS calling feature to yield shiny Pokémon. Furthermore, as the chain increases, there is a higher chance of a Pokémon with perfect IVs to spawn.
Preparation for SOS Chaining
While a Pokémon will naturally call for help when its health is low, this will only occur once, so we need a way to activate constant SOS calling from that Pokémon. We can force this to happen by using an Adrenaline Orb.
These can be found in all Pokémon Centers after beating the third trial - Kiawe’s Trial on Wela Volcano - and cost $300.
A Pokémon with 
False Swipeis also highly recommended to bring the Pokémon down to 1 HP. 
Breloom and 
Gallade are great candidates due to their high Attack stats and sleep inducing moves 
Spore and Hypnosis, respectively.
Starting the SOS Chain
First, use an Adrenaline Orb to force indefinite SOS calls for help.
Next, bring the target Pokémon down to 1 HP using False Swipe.
Now, you want to keep the Pokémon with lowered health alive so that it calls for help, and another Pokémon will come to its aid every time.
Continue knocking out the new Pokémon that arrives until a shiny one appears.
What are the Shiny Odds?
In short, the bigger your chain is, the better the shiny odds, maxing out at 1/315 without Shiny Charm and 1/273 with the Shiny Charm.
The exact shiny odds are below:
| Chain Length | Shiny Rolls | Shiny Chance | Perfect IVs | Hidden Ability |
|---|---|---|---|---|
0-10 | 1 or 3 | 1/4096 or 1/1365 | 1 (Chain 5-9) | 0% |
11-20 | 5 or 7 | 1/820 or 1/585 | 2 (Chain 10-19) | 5% |
21-30 | 9 or 11 | 1/455 or 1/373 | 3 (Chain 20-29) | 10% |
31+ | 13 or 15 | 1/315 or 1/273 | 4 (Chain 31+) | 15% |
What Pokémon Are Exclusive to This Method?
While you can hunt many Pokémon with this method, some are exclusive to SOS battles.
| Exclusive Pokémon | Called by | Exclusive Pokémon | Called by |
|---|---|---|---|
Pikachu | Pichu | Sudowoodo | Bonsly |
Clefairy | Cleffa | Espeon | Eevee |
Jigglypuff | Igglybuff | Umbreon | Eevee |
Slowbro | Slowpoke | Sableye | Carbink |
Gengar | Haunter | Whiscash | Barboach |
Chansey (Sun & Moon) | Riolu | Glalie (Sun & Moon) | Snornut |
Seaking | Goldeen | Shelgon | Bagon |
Starmie | Staryu | Salamence | Bagon |
Electabuzz | Elekid | Happiny | Pichu |
Magmar | Magby | Lucario | Riolu |
Gyarados | Magikarp | Garbador (Sun & Moon) | Trubbish |
Snorlax | Munchlax | Pangoro | Pancham |
Dragonair | Dratini | Mareanie | Corsola |
Dragonite | Dratini | Hakamo-o | Jangmo-o |
Crobat | Golbat | Kommo-o | Jangmo-o |
Tips and Tricks
You have to swap the main calling Pokémon out occasionally; otherwise, it will run out of moves, struggle, and faint. To fix this issue, you can either keep track of how many Power Points (PP) it has or bring another Pokémon in your party.
Trevenant is a great Pokémon, as its Ghost-type gives it an immunity to Fighting and Normal-type moves. The recommended move set for this Trevenant is:
- Trick
- Skill Swap
- Two other moves of your choice
Its Hidden Ability, Harvest, is also necessary for this to work. The Trevenant needs to hold a Leppa Berry, which can be given to it either in or outside of battle, so don’t worry if you forget. To start with this method, use the move skill swap on the Pokémon you wish to be the main. This will give the Pokémon the Harvest ability, and then Trick will be used to give the Pokémon a Leppa Berry. Once this is done, you’ll be set up to hunt endlessly!