>>13979860....really?
Must i explain?
They can't ever let it be possible for someone to go in a past game, use a moon stone on an eevee and go, "Hey, wtf gf y u no evo"
That's why every generation introduces a new way of evolving, so the generations before it could explain these Pokemon not having the option to evolve.
If a Moon Stone evolved an Eevee, someone would've figured that out in R/B days. That sort of concept.