- What is a Secret Shiny?
A Secret Shiny is a rare shiny particle variant. Secret Shinies appear the same as normal shinies but with a different particle effect. This particle effect replaces the normal shiny particle; you can't have a pokemon with both the Secret and normal Shiny particle.

- How do I get a Secret Shiny?
Secret Shinies only appear in single encounters or naturally-occurring hordes (not in hordes summoned by Sweet Scent and not via breeding). When you encounter a shiny pokemon, there is a 1/16 chance that it is a Secret Shiny instead of a normal shiny.

- Does Donator Status/Shiny Charm affect the chance of a Secret Shiny?
No

- What happens if I breed a Secret Shiny?
You can breed Secret Shinies with normal Shinies and the Secret Shiny particle will be passed on to the baby. Remember though that you cannot have both the normal and Secret Shiny particle on the same pokemon.