uhh, marth's pretty hard to waveshine. The problem I have with waveshining marth is how far he goes from the attack. to compensate, I throw a jab into my waveshines, just to add damage and range. It's pretty effective, esepcially against falcons, but works just fine against marth. None the less, going for a full-on waveshine combo against marth isn't really a good idea. keeping the waveshine consisitent can be quite a task against marth, and there's a greater chance he'll break out and end up hitting you then you actually achiving anything. if you want to do shine combos to a marth, keep it simple, like shine-usmash/grab/whatever airal you can get in. I, as I said before, prefer the jab.