I can give any breedable pokemon or ultra beast (or anything from the Cosmog line) of your choice having: any level, any evs and ivs, any nature, shiny or non-shiny, as per your choice.
The stats for the Silvally/Type:Null don't matter, it just has to be shiny.
I can give a 10% Zygarde as well, but it will be strictly non-shiny.
I may be able to give a specific item as per your choice as well (there are limitations though)