If you encounter a "Save data is corrupted" error, it is often due to a mismatch in game updates .
Never use a 100% save file before beating the story. It can break event flags and lock you out of cutscenes. Always start a downloaded save on a fresh profile or after finishing the main campaign. Yo-kai Watch 2 Save File Download
To use a downloaded save file on a physical 3DS or 2DS, you must have Custom Firmware (CFW) installed. Checkpoint If you encounter a "Save data is corrupted"