You could do that
But the biggest problem is that Marth is right handed and Link is left handed, so you'd see Link smacking people with his shield.
I think there's a Link rigged over Marth's boneset somewhere in the vault. Let me try to find it.
EDIT: Can't find it

might have been taken down...
Eh? Link smacking people with his shield? I meant is it possible to have a Marth hack with all of Link's moves instead? Like can I just swap out the .pcs, .pac., and fit motion to do this?