My suggestion would be to slow down a bit. Really, you don't always have to be in the air with Marth. If you miss, don't always go for a second try, retreat and restart. Facing any defensive character is all about patience. It takes patience to win against characters like Dedede and R.O.B. when you can't out camp them.
@Bad. My Dedede has a tendency to do that. Future reference: I'm a tourny fag, I despise item matches.
Also, don't up-b immediately off stage. Get near the stage first. =p Your connection is impossible to land aerials in, my Wario and Kirby felt gimped all to hell -.- "You suck" or whatever it was as a taunt really turns people off. Might want to change that.
My Creations in Modnation Racers! Check zhem!
http://community.modnation.com/en-us/players/IvoYaridovich/creations
