- Stalk up with Pokeballs, Leppa Berries and Adrenaline Orbs

-Find a Pokémon that has the hidden ability Harvest (for example, Exeggcute)

-Teach it Bestow and teach it Skill Swap

-you can also have a Hypno that knows Switcheroo that is similar to Bestow, you still give it the item the Pokémon is holding (in this case a Leppa Berry) but the only difference is that it trades items so if the wild Pokémon is holding an item this will be best for you.

-let it hold a Leppa Berry

Once this is done, you are able to Bestow the Leppa Berry to the wild Pokémon. And Skill Swap will Switch abilities so the wild Pokémon you are Shiny Hunting for will now have the ability harvest and a Leppa Berry, it will be able to stay in battle forever so make sure not to kill it.

-Have a Pokémon that knows False Swipe

-Use False Swipe on the Pokémon with Harvest and Leppa Berry (This will get it to 1 hp but be aware that some Pokémon can have damaging moves such as Take Down)

-the Pokémon will start calling for help

Note: Not all Pokémon are able to call for help such as Minior

-if the Pokémon doesn't get any help, Don't Attack! Use Adrenaline Orb which won't have any effect because it can only be used once during a battle so you will not waste it. That'll waste your turn which isn't bad. Keep doing this until the Caller calls for help again and it gets an answer

-Then Attack the Pokémon that is called in (not the caller!)

-Soon you will encounter a Shiny so watch for those Stars because some Pokémon are hard to tell such as Igglybuff. I could have failed mine if I didn't watch for the stars.

Sos Chaining Chances

Perfect IV's

Chain length 0 to 4: No guaranteed perfect IVs
Chain length of 5 to 9: 1 guaranteed perfect IV
Chain length of 10 to 19: 2 guaranteed perfect IVs
Chain length of 20 to 29: 3 guaranteed perfect IVs
Chain length of 30 to 255*: 4 guaranteed perfect IVs

Hidden Abilities

Chain length of 0 to 9: 0% chance of Hidden Ability
Chain length of 10 to 19: 5% chance of Hidden Ability
Chain length of 20 to 29: 10% chance of Hidden Ability
Chain length of 30 to 255*: 15% chance of Hidden Ability

Shiny Chance

Chain length of 0 to 69: ???
Chain length of 70 to 255: Three extra rolls for a shiny spawn.

The game has the maximum chain length of 255. This means that it is possible to chain up to 280, and only catch a Pokemon with 3 perfect IVs.

This is the method I use to Shiny Hunt in Sos so it works. You may be able to bestow a Leppa Berry and use Skill Swap to give a legendary the ability Harvest to make it easier to catch and keep it in forever without it struggling and fainting itself, but I sadly never done that because I only have my Harvest Alolan Exeggutor in Pokémon Moon at the moment but I've seen it on Youtube.

Pokémon Sun and Moon and Ultra Sun and Ultra Moon Shiny rate without the charm- 1 in 4096 (I don't have the charm yet in Ultra Moon so this would be the shiny rate for me in that game)

With the Charm- 1 in 1365 (I have the shiny charm in Moon so this would be the rate for me in that game. I have a higher chance to get shinies in that game)

[There should be a GIF or video here. Update the app now to see it.]

The video will explain it and show it better from Adrive on Youtube. He actually got me into shiny hunting honestly.

Good luck on getting shinies. I hope this helped make Sos hunting easier. If you have any questions, you can ask me.