When Brawl was coming out, we didn't know if Marth was still in, so I didn't know I'd be keeping him as my main from melee. Also, I've loved Metaknight as long as I've known him, so I was intending on maining him, but the new Marth won me over instantly, and I started to second Meta-Knight.
As play developed, I dropped Meta-Knight, and really began to favor Mario. He plays VERY similar to Marth in some ways (I know he doesn't spam fair or side B so hear me out)
Mario's upper cut, while lacking range and K. O. potential, is very similar to Marth's Dolphin Slash. His front smash has as much range and power, and his side B is used for midair pivot/ fall breaking similarly.
Whereas Marth has bad matchups, Mario has good, now being able to utilt juggle and bair very powerfully.
Unfortunatly, another similarity the characters share is their weakness from below. This may subconciously be one of the reasons I'm beginning to stick to Falco. His gun range, bair game, awesome Fsmash hitbox, chain grab for easy damage, easy dair spike, interrupting down B, linear horizontal recovery, and reliable dair take away Marth's main enemies (those being no long range, no deflector, semi-gimpable edgehog, and weakness from below as his dair isn't good in standard combat)
So I use many characters, but Falco might be your man if you need someone to balance Marth. My personal top line up is:
Marth
Mario
Falco
