I want to hear why you think that samus has an advantage on marth though. That sounds a little fantastic, but if it's true then there will be a whole lot more interest in her!
Haha, youre right, it is a little fantastic. I wouldn't say its a big advantage, probably almost even. But it is definitly not in Marth's favor. Let me say first that I have the most experience with samus and marth than any other character, and my roommate and I just got the 10,000 match notice a little while ago, so weve got plenty of experience.
So here are some points I have about the matchup, feel free to argue and discuss:
-Samus takes away Marth's main damage builder, his juggling game. Samus is both heavy and floaty, making her juggle resistant but still able to survive at higher percents.
-Marth's ground speed is above average, but his air speed is still a joke. This makes it very difficult for marth to weave in between homing missles and super missles while approaching. A good marth will actually do sh double fairs to cut through all the missles, but this gives samus an advantage by forcing him to commit to an attack.
-Marth's air speed and relatively tall height make him a very easy target for zairs, your best tool in this match.
-Marth's light, at about 90 percent you can start comboing a well timed zair into a charge shot (just tested, if timed right he wont have time to tech the ground)
-Don't tell any of the other character boards, but samus kinda gets ***** by anyone who can approach from high over missles and zairs then come down on her with a powerful attack (ganon destroys samus in brawl+, truth) Marth cannot do this, his dair is crap for anything but edgeguarding
-Samus straight ftilt outranges all of marths ground moves but sheildbreaker. And dtilt outranges all but fsmash.
-Neither character can edgegaurd the other well, marth's recovery is pretty spike proof. Just stand back and double homing missle. If you knocked him off pretty far, its sometimes fun to rar off the stage and tether the edge as he uses upB to recover, you'll either gimp him or follow up as he lands on the stage.
-Ultimately, Marth is still an incredibly good character but if you play a solid samus game (and use a lot of retreating zairs for spacing) marth will have a hard time getting in. Overall I'd say its 55:45 samus overall. On FD Id say 60:40 samus and on WW Id say 70:30 Marth's favor lol
P.S. New samus usmash is great, and is there anyway to allow homing missles to pass through platforms?