you can also Ftilt the missiles, and that way you don't stop aproaching to her
i think Nairing is a good aproach since most samus like to spot dodge, it's hard to dash-dance grab her because the dodge is too fast and a missed grab will get you a Dsmash or anything bad
side B works well also against spot dodgers
and fair isn't a bad aproach either, just be careful
i think every marth move suits to a situation, when they wavedash too much, you can go and Dash attack them, or wait with Dtilt
well i think all this stuff can work with a lot of chars
against floaties, tipper Dsmash works very well, they die in low percentage upwards :D, it's like fox's Usmash, but it's hard to get the tipper, i like doing it on the edge, when they get up with the shield button, you face against the edge, so if they just come up, they'll get normal hit, but if they do the shield button, they die