it probably loads the saves as some random data if it's encrypted.
i tried to use a friend's savefile for ikkitousen since he had much more stuff unlocked and the game's a nightmare to clear (takes ungodly amounts of time to beat arcade mode on hard, and you have to beat it with every single character. you have to beat it on hard to unlock the extra outfit, and then beat each difficulty level for extra colors), but it got randomly scrambled instead.
some characters got unlocked, others got locked even though they were supposed to be starter characters, available from the beginning, key settings and options got scrambled, missions randomly got unlocked too etc.
i tried to use a friend's savefile for ikkitousen since he had much more stuff unlocked and the game's a nightmare to clear (takes ungodly amounts of time to beat arcade mode on hard, and you have to beat it with every single character. you have to beat it on hard to unlock the extra outfit, and then beat each difficulty level for extra colors), but it got randomly scrambled instead.
some characters got unlocked, others got locked even though they were supposed to be starter characters, available from the beginning, key settings and options got scrambled, missions randomly got unlocked too etc.