So out of curiosity, what in particular hurts Dedede overall as a character? I don't doubt these claims, but I haven't ever really heard what's really wrong with him besides "Megaman".
I think the only real problem is that several characters that could do fine approaching him (yoshi, zss, fox, sheik, diddy, blah blah) have just enough projectile threat to force him to approach. The projectiles are quite low commitment and force dedede into positions where they can suddenly switch gears to offense. If they didn't open you up they scurry off and put the process back in place.
Contrast this with characters with a much better set of projectiles but worse buttons and rush down - villager, DHD, Robin, links etc - who also force an approach but don't pounce like a hyena at a single sign of weakness. It feels fine to approach them. It just looks horrible in some cases since 80% of the time you are losing neutral, but 20% of the time you have to get 80% of your damage. Imagine it like top trumps, you only need a 1/10 projectile to force dedede's somewhat clumsy approach, if you have 10/10 projectile game that's fine but you probably gave up a bunch of power elsewhere you could exploit dedede with.
Likewise the match up with fellow non projectile characters are great, you can play around with spacing and there's no rush to get in. You don't have to sit still but you don't get forced to jump or shield stuff either. (Gordo is not a projectile, except during advantage time.)
Coming from someone who doesn't main Dedede, I would think his problem is similar to Ike in that he has a 'decent' kit with a lot of bad match ups. I can't imagine his neutral being that bad. His forward tilt is incredibly big and his jab seems decent, and jab 2 leads to a grab combo. Multiple jumps should help the neutral game also.
What do you have to say about this.
His neutral is pretty bad. Ftilt looks a lot scarier than it is, it has surprisingly far out hurt boxes and unless spaced perfectly often ends up missing hits and doing 2-7% damageish. That might fly for a hit from sheik but dedede needs more. It also is unsafe on shield and in some cases on whiff (hi sonic!).
Multiple jumps are good for getting out of juggle situations. And you do need to jump around a bit in neutral to threaten coming down with a meaty bair or punishing any blind offense with a nair. Not exactly risk free options though, you are just trying to get enough respect to push the opponent back. Once you get someone at the edge of the stage they are forced to move past you, and that's where being slow and fat doesn't matter - you catch their escape and get an opening finally yay.
That's just dedede's entire game plan. Put people in a situation where immobility is irrelevant and fat hitboxes are king. Juggles, edge guarding, gordo ledge traps, post-down throw mix ups or flat out stage control. In each case they are being forced towards you and your big hitboxes and need to do something punishable to get out. If they mess up they go right back to disadvantage.
Words words words this is like and amazing ampharos post, sorry. Not talked about dedede in a while and wanted to frame his strengths/weaknesses again for those not in the know. I'd say the way to see all this in action rather than just forum post theory is go watch videos of j dawg. His dedede is great and we independently discovered a lot of the same strategy, except he is actually good at the game and has way smoother movement.