It's not always dealing damage that's the issue, but being able to do anything against opponents who constantly flinch and interrupt you every other second. No flinching means plenty of uninterrupted damage and time to charge up the right attacks.
I think there’s a legendary primary with unflinching/slow Armor that has 2 or 3 slots. I’d say use that and have the shine sprite and wind fish support in your setup for maximum effect. Especially if you’re using a heavy character like Ganondorf