Typically it depends on what you're looking at, but past-life plots are generally workable but we suggest speaking with the mod team first if it's a big thing. Before time of Savior is typically off-limits.

Zorua shifters will likely be under the same general limitations as Ditto shifters, pick either humans or Pokemon and that's what the ability can apply to. Hairstyle would definitely be applicable for the detail that can't be hidden.