@ Riot; Yes Marth has a boost smash, sorta. Does it go far? No you can barely notice it :p You'd have better luck hyphen smashing instead.
@ Jski; Boost smashing is pretty hard to do. See it's kind of like a fast 1,2,3 motion(consecutivly, i mean). There are two easier ways to do it. With tap jump on (standard controls). I do it with personal controls, set the Z button to attack. Then you do these as fast as can in consession...
1. Dash
2. C-stick down
3. Control stick(the one you move with) up
4. Z
you don't have to set it to Z though. Any button on the same side will work. The timing takes a good hour or two to get used to so be patient ^-^