Zelda vs Dedede huh? There's a really good Zelda at my locals (Face) who I usually end up in winners or losers finals with, and I myself haven't really been able to beat him yet, but I've been figuring out the MU, so hopefully I can help you out there.
I'm only gonna watch the first two games for now, but I may watch the rest of the set later. Also, I guess I'll just point stuff out as I go then talk about the MU afterward.
First off, at about
50 seconds in, you are met with a dins at the ledge. Always, always, always get rid of dins as fast as you can, unless it'll put you in danger. All of your aerials and normals with break it, and in this situation, fair or waddle throw would have worked best.
Next, at
3:30, you dash attacked at her in neutral, and got punished for it. You did this again about 30 seconds later into the set, and you were met with similar results. Dash attack really isn't too good a move. so in situations like this, you're better off f tilting. You can use dash attack as an edge guarding tool if Zelda teleports to the ledge and over extends slightly above, since the armor on the dash attack should take the hit from the teleport.
Just noticed that you did actually try and use it to edge guard at about
4:15, but you should use it more when they're right above the ledge, not going onto the stage. Dash attack still isn't usually your best option, so I don't always encourage it, but if you are going to use it, again, use it when they're teleporting right above the ledge (you can usually tell this is going to happen when they teleport straight up from below the ledge, since it can be a hard sweetspot.)
Next, you counter picked Battlefield. Counter picks can be preference, so if you like that stage, more power to ya, but I feel like Zelda has the advantage on this stage. Getting Zelda on small-ish stages can be good since you can avoid dins with it, but dins can also shut out your platform movement on stages like this, and the platforms can prevent waddle camping from certain angles. On top of this, a good Zelda can use the platforms for ledge cancelling teleports. Personally, I would have gone Green Hill Zone instead, since it's got similar dimensions and less platforms.
Don't have a time stamp for this one, but great job mixing up recovery. I had a hard time telling how you were going to recover with waddles and up b, and so did the Zelda, so you seem to be pretty good in that aspect (aside from an SD or two, but hey, happens to everyone)
Just something real quick, I noticed you were missing a lot of L cancels. Not sure if this is just inexperience or nerves, but you should work on that a bit.
As for the normal MU, in neutral, try and waddle camp a bit more. This is hard to do against Zelda, since she has more control over her own projectile, and it does almost double the damage of your own, but if you mixup where you're going to be and break the dins before they can explode, you should be able to waddle camp fairly well while setting up waddles for approch/retreat with waddle dashing (on that note, I've been experimenting with rising z tosses in this MU, and it seems as though a downward toss followed by an aerial is a great mixup on Zelda, since it can be hard for her to cover without just shielding). If she tries to approach, you can keep her out with fair, f tilt, bair, etc..., just be careful with shielding, since 2 or 3 well placed lightning kicks can almost break your shield (this is why I prefer f tilt to keep her out when you can, since it has more range then Zelda and is disjointed. Fair can do the job to, but between the short hop you need to get it out and the actual move itself, it's slower and has less range than f tilt).
Now, for edge guarding, I noticed you were getting caught by teleport a lot when you went to position yourself to punish this. I've found that if you can't get out and fair her before she teleports, and you're not sure if you can get into a good position to punish in time, go where you think she'll be, shield the teleport, short hop nair, and follow up with whatever you see fit. Edge guarding Zelda isn't as simple as it is with most characters, so you really just want to land in small hits that get her off stage until you can either fair her before she teleports or just knock her right out of the blast zone. Also, I did notice you edge guard her with down smash a few times, which is good, so keep doing that when you can. Since Zelda is so floaty, down smash can be a good kill move on her, plus it can cover both sides of you with a disjointed hitbox.
Also, try to limit her recovery options with waddles and ledge grabs if you can. Maybe throw some waddles at her while she's off stage to try and force her to recover early, and grab the ledge every now and then to force her to teleport back on stage (this isn't the best option, unless you have a waddle near the ledge to get to where she teleported faster, or if she has to teleport close enough to the ledge where you can drop off, double jump, and fair her).
Sorry if I rambled a bit there :/ Also, not the best advice since I haven't actually beaten that Zelda player just yet (a lot of our matches have been close tho), so yeaaaa...
If it helps,
here's the last match I played with that Zelda I mentioned before. All johns aside, I really wasn't playing that well that day so it's not the best example. I don't expect it to be up anytime soon, but there should be a VOD up eventually of one of my better games against him
Again, sorry for rambling and such, but I hope it helped.
EDIT: Also wanted to mention, you should almost always DI Zelda's down throw in the opposite direction that she's facing. It'll send you fairly far away, making her only follow up a tech chase.
EDIT 2: I forgot to mention, if you can read where a teleport is going, or get a platform tech chase, up smash is a fantastic kill move against Zelda, since it covers a lot of space and has a lot of kill power. Also disjoint.
EDIT 3: YAY MORE EDITS. I noticed that you followed up d throw a lot with f tilt, but try not to do that as much. You can get more off of a tech chase, although that can be hard against Zelda with her amazing tech roll and what not. Use f tilt after d throw if the d throw is going to knock them off stage and you don't have enough time to run off and fair.