I want to transfer my over 50 hours devil survivor save to gateway, but it looks like its pretty difficult. I tried the following method with no luck: in diskwriter I made a backup of the game I copied said backup to gw card after renaming the save with the id title of the game and I put in the internal sd card, but the save was corrupted.
It doesn't work that easy. Sky3DS saves are encrypted just like original ones. GW saves are not encrypted. GW is not able to dump the saves of sky3ds (crashes with 0xFFFFFFF) thus not decrypting them.
For this task SafeDataFiller is necessary but it only works on CFW and with games which encryption is <6.0. It doesn't work with GW because in GW mode (where SDF works) retail cards are not detected. In classic mode those cards are detectedk but SDF doesn't work.
PowersavesPro also works, because of encryption, but the game headers needs to match and be private or PowerSaves goes nuts when you put in the Sky3DS. Be careful with NON-EEPROMs as well. They have savedata on the 3DS SD card you need to transfer.
Been having NON-EEPROM troubles until I figured that out. But still too lazy to care. But once you got it up and running, using just DiskWriter on NON-EEPROMs will not work.
Might also want to look into SkyArmyKnife. Good stuff there.