Emulator

Current Implementation of mGBA Netplay uses the Host's save data for all connected GBAs.
For games where player save data matters, having to manually send save data is both inconvenient and error-prone.
The save files need to be renamed manually, and placed in the correct folder every time.

Netplay already has the "Hide Remote GBAs" option which preserves hidden information for turn-based multiplayer.
This would effectively make that feature more complete, by preventing the host from "save-peeking" in games like Pokemon.

Suggested Implementation would add another menu option called something like "Request Remote GBA Saves."
With this option enabled, trying to launch the game would prompt the Host/Clients with GBA Controllers enabled to select their preferred GBA save file.
If necessary, the save files are then renamed correctly and placed in the appropriate locations.
After which, Save/Code syncing would proceed as normal and the game launches.