plugin adds a reader -> reader checks if it is a non-PKHeX.Core save type (they'd implement their own savefile/etc type) -> returns a matching save object if so
basically bypasses the base PKHeX logic
GCI, DSV, DUC are already supported, so I've written the abstraction for those and seed the Handler list on startup.
Can add a new class with recognition via SaveUtil.Handlers.Add(myHandler);
