If you could hypothetically bring Hisuan forms into Scarlet/Violet, then breed them, you would get the standard forms, unless a parent with the Hisuan form is holding an Everstone. Just like passing down a Nature, the regional form will always match a parent holding an Everstone. This is not limited to just Hisuian forms, either. In Scarlet/Violet, there are NPC trainers who will trade certain regional forms. There's one that takes a Paldean Wooper in exchange for a standard Wooper, and another that takes a standard Meowth in exchange for a Galarian Meowth.
However, there are some forms that would not be obtainable. Quilava, for example, would evolve into a normal Typhlosion, because the Quilava is not in Hisui when it evolves. The Everstone wouldn't help in this situation, because it would simply block evolution altogether. Another example would be Ursaluna. You need the Peat Block item to evolve an Ursaring. Without that item, evolution is not possible.
Interesting side note, because Ursaluna exists, Ursaring can make use of Eviolite, since it still has a higher evolutionary form. We just lack the item to trigger it.
