pokemon sun and moon shiny odd discussion

[OGaryOak]

I believe the chance for encountering a shiny pokemon in generation 7 is a 1/4000 chance as stated by the in game npc 
The shiny charm gives you three more chances to produce a shiny pokemon  4/4000 =1/1000 
This is only applied to random encounters and eggs
(correct me if I'm wrong) 
SOS chains are entirely different 
Here is the information that's available for it now but I'm sure more will develop as time goes on 
Sos chain shiny odds 

and as always 
may the shiny odds be ever in your favor