Ophie
Salingerian Phony
The Lental region has every Vivillon wing pattern available right near each other, so there is precedent for this.My idea is to make certain patterns only appear in appropriate parts of a region such as Polar and Tundra being found exclusively in snowy fields, Ocean in large aquatic areas that have sandy beaches, and Sandstorm in deserts. It’s sort of like the Shellos line in Sinnoh but with more locations.
What I had in mind, though, is a save bonus of sorts: if you have a New Pokémon Snap game save with at least one picture taken of every Vivillon wing pattern, an upcoming game would allow you to pick any one Vivillon wing pattern you'd like or set your game to a particular Vivillon wing pattern (under the condition that you can't change it later).
That being said, extreme regional exclusives don't seem to be going away any time soon, considering Pokémon GO has just pulled another one, with Furfrou's Pharaoh Trim being available only in Egypt.