I'm going to preface this by asking you to please forgive my general lack of knowledge of competitive Brawl. I haven't played competitively in nearly six months, and when I did I only used a handful of characters. So you'll have to excuse me if I say something "controversial". I'm going mostly based on memory trying to get back on track.
With that said...
Just what is so good about King Dedede? I mean, for the life of me I can't think of any useful moves aside from his chain grab, his f-tilt, his b-air, his recover move and his waddle dees. Same thing with Lucario, the only good moves I can think of are his neutral A combo, his f-tilt, his u-tilt, his force palm and his aura sphere.