Unless if you owned the game, then it's not legal.
that only applies to some countries. and even then ROMS can be either; private, abandon-ware,unlicensed, and i think official license or something. and the rules change for each one.
and for old nin/snes games we have no way to know what game falls under what, because the companies haven't commented 10 years ago on them, and they wont be starting now.
it would help if the laws were enforced, but it isn't even clear IF its illegal.
although it IS clear, you cannot make money off them.