Technically,
doesn't really need a secondary for any matchup. I don't think any matchup is worse than even for Marth at top level, not even against Sheik, as long as you are good enough. But let's be realistic, it's hard to be playing your best with one character all the time, so with the harder matchups, having secondaries aren't ever a bad idea. So here are my possible secondaries for any matchups that can be considered challenging for Marth:
You really don't need a secondary against
and
, except for maybe Fox on Dream Land, since Marth is easily the best counter for both of those characters.
For
, you could choose Sheik, Fox or Falco.
For
, you could use Fox or Puff. Or if you are adventurous, you could go Ice Climbers.
For
, go Fox. Pretty easy.
Contrary to what some people have said, I don't think
is a bad matchup for Marth, but if we say that it is, learning Peach or Ganondorf would certainly solve that problem, but you could also use Fox too.
I think Marth wins these matchups, but if you want a secondary for
and
, I'd just go to Fox, pretty simple.
For the more odd matchups like
and
, I think Fox and Falco are probably the best secondaries, but I still think Marth wins those matchups regardless.
For
, I'm not sure what you could use as a secondary if you are Marth because Marth is supposed to be one of Samus's worst matchups. So...I guess Sheik or Puff? But still, Marth wins that matchup for sure.
And some people have mentioned
as potentially being a difficult matchup for Marth, which I don't believe, but I guess Fox would solve that problem too.
So in total, I think you could use Fox for all those matchups, except for maybe the Samus matchup, so having Fox as your only secondary would be ideal. If you want to go even further and start dual-maining, a lot of people, including PPMD, say that the best dual main combination is Fox-Marth. So learning Fox isn't a bad idea if you are a Marth main. But like I said at the beginning, you can still technically just solo main Marth without using secondaries. It wouldn't be easy, but you could still do it.