wooo, slow down guys, be aware of what Dedede has in the match-up.
Dedede doesn't die, first of all. Ever. Lets get that out of the way. You'll have to wait until at least 120% for your **** to start KOing when you hit him fresh from offstage with bad DI. The guy's a frikkin' fat-***. Getting rid of Dedede will be a pain. The biggest thing you have to your advantage is how easy it is for you to do damage, so at least you can get him to the KO range of about 200% without much effort, but in that time, you'll take the 0% necessary for him to KO you, so it's a bit of a trade-off.
But on the other side of the coin, the guy's pretty good at camping you, and outranges most of your arsenal, and he only has to PS that (easy). And yes, he can't CG you, but if you tech away, you'll tech right into a dash grab. Tech in place, you'll tech right into a SC grab. Tech towards him, you'll be caught in a pivot grab. Miss the tech, and he'll dair you. Dedede's tech chase game is at its prime in this match-up, because all of your tech options are covered by his dash speed plus his monstrous grab range. Try it. I was flabbergasted the first time I teched away from the guy. He didn't even have to reach for it. I literally teched right into his hand. Finally, he's got a **** good edgeguard. It's not too bad for ZSS, because you're much more mobile, but you really have to watch out for that bair. It's about the size of a Mack Truck, and if you get hit by it, you're completely boned.
I'm not saying the match-up is in Dedede's favor. Just be aware that he's not helpless in the match-up, and you will have to work for it. 6:4 on a good day.