[Question]A way to back Up Save Data and Injecting it back?

Hi Guys,

Is there a way to back up all my saves, both physical cartridges & eshop download games and then reinject it back on the system? I want to format my o3DSXL and my SD card so I can downgrade it (I did this on my o3DS and it works, so im planning to do the same thing).

Thanks in advance