I only watched the first couple of video's, I'll probably finish the rest later. For now though I'll say that you did pretty good. You seem to have a very offensive DeDeDe, which seems to work for you. Personally I prefer a more defensive style, but if it works for you then stick with it.
As far as critiquing goes I don't really have a whole lot to say. I noticed a few regular dash grabs which should have been shield canceled, but not too many. I also noticed that sometimes that sonic player was living to pretty high damage. I find that Sonic has a pretty good recovery and is fairly hard to edgeguard, so I recomend going for the over the top kill if you can. DeDeDe's Utilt is very good at doing this, and it's probably the easier killing method if you can work it in.
Edit: Wouldn't ya know it, I watched the next video and I saw an Utilt kill, and no missed chaingrabs. Very nicely done sir.