its all pretty complicated
first thing first, if the game uses 6.x encryption(pretty much all games released with 6.x+ on cart) and was played on a retail console.......no, there is no way to use that save....but if the game uses 6.x save encryption and was played in classic mode you can go to step 2
secondly the save will only work if its either a nand saving game i.e pokemon or animal crossing or the save is 512kb when dumped, if its smaller than 512kb it will not be usable
and finally if you pass both them barriers you will need to dump the cart the save is coming from and rename it to (game name).3dz, it will not work unless you have a dump from the exact cart the save came from and rename it to .3dz