When I actually make an organized thread ill try to throw in what I remember the knockback of attacks being, but itll be on a scale like (blah, ok, good, really good, and toe).
Zelda has a sturdy KO game, everything Luthien said is more or less true. Off the top of my head, Id say I killed with: Up-air, Over B, Down-Air, Forward-Air, Back-Air, and Forward-Smash. Nice list, huh? Up-smash and up-tilt send high, but kill at higher %s than the rest of these. Down smash is very similar to melee, and the rest of her attacks have fairly low knockback (though, I suspect forward tilt is really good and I just havent landed one yet)