Shadowlink, my electricity went out, so this is kinda late...
- She forces him to approach. That means she's not approaching as much, if at all. That means she has gotten rid of one of her worst weaknesses.
- She kills him at around the same %s he kills her. That's saying something. It also bears noting that, being a large and slow target, he's not getting out of the Usmash. If he gets out of the Fsmash, he's punishable long enough to be hit by something else. This goes for everyone actually, but I emphasize it here because Zelda does not care about the woes of Fsmash and sometimes Usmash.
- Unless she's knocked away or doesn't know what she's doing, Zelda should be punishing DDD's recovery all the time with Usmash/uair/edgehogging or Din's if she can't reach him for some reason. This is actually a fact of the match-up and not just "theory." Zelda's recovery is exploitable as well, but she has a better chance at getting past DDD (especially on Battlefield and similar stages) than DDD does against her.
- I don't know DDDs true combos, but Zelda has dtilt -> bair on a trip, dtilt - > fair on a trip (in case bair is stale), the above /without a trip if you have the proper frame advantage on him (which stacks up perfectly when a fresh bair will kill), and the usual low % stuff. This means that Zelda has a setup to kill him at 60-80%, depending on stage positioning. This isn't a "rare" thing to do, either. It's very reliable.
- She beats his dair if she can react to it at all times. In fact, for the most part, she can always challenge him in the air and trade or win. The only time she can't do that is against his uair with her dair. Now, you may think that talking about what beats what isn't too important, but when Zelda's aerial game of all characters gives some other characters serious woes, what you end up with is an interesting situation. This, combined with being able to force an approach, means that you can indeed keep Zelda in an advantageous position for the whole match.
- There's the other thing that Zelda doesn't get chaingrabbed. Yes yes, he can do other stuff, but getting rid of one thing of his >>> nothing.
There are plenty of videos of this match-up on the Internet. For the most part, this is how a lot of them go:
- Zelda harasses with Din's, sometimes taking a little damage, sometimes not
- Zelda waits for the inevitable ftilt because that's all he can do... that or she can just wear his shield down and get an easy poke thanks to him being so big
- Zelda gets a lot of damage in
- Someone gets knocked away, and it repeats again as necessary depending on the player
- Stock either ends below 100% because lightning kicks are ridiculously easy to land on him, or it ends below 150% because the DDD is doing his best to not get hit by them, even though it's still easy to get shieldstabs on him
Obviously this isn't how it goes for every single stock, but during all of this, DDD has to play his typical bair/grab game because Zelda can scrap the rest of his stuff with Din's or ridiculously strong aerials. Being slower than Zelda in everythign but falling speed doesn't help. The match-up is at least 6:4 in her favor. If more Zeldas start implementing their guaranteed lightning kick setups and if more Zeldas played a super campy game for once (since she can't out camp most of anything), the match-up is a lot worse.