i noticed some of the names have an S after them, i got a shiny shinx as it has a star where my other one doesn't what does the S mean example (leafeon S)

Likely means "Sell" ? The SHINY star and the mark for SHINY in the market have no relation to what people name their pokemon

one guy adds S to all he sells and so far all he sold to me was bugged and impossible to "release" xd