You guys dont need secondaries to cover MU's, its not a good idea or mindset imo. Its not a bad idea to dabble in other characters or anything, or play your Bad MU from a character that does well in it so you know why they do well in it. "Make your characters bad match up your best match up."
Generally if you aren't playing a bad character, you have tools and counterplay to the opponent (unless the opponent is 3.02 M2 or any iteration of sonic) so you should be able to play the MU in your favor. Smash MU's are so dynamic compared to other fighting games, and generally people over-exaggerate match-ups and boil them down to too little. "Oh, shiek gets one grab on marth at zero, she regrabs to 30 and gets and ftilt? Punish game completely in her favor, 60/40 at best for marth." Idk, I've been reading all the character MU threads and its frustrating to read people say "I can't deal with X character in X situation, this MU is horrible, I need a secondary that wins X situation" instead of "I can't deal with X character in X situation, so I'm going to use Y tool that my character has to avoid X situation the best I can." This isn't smash exclusive, every community does stuff like this, but that doesn't make it okay or any less stupid or less inhibiting to growth. Its like people think characters are static in their playstyle and goals for every MU, and when the opposing character seems completely built to counteract that goal, instead of adapting their own play, they look for a different character with a different static goal.
This rant isn't directed at you guys though.
Idk, its just a horrible pattern that shows up in new players no matter how many times people make huge threads about it, and It rustles my jimmies that it hasn't been extinguished yet. I still see it in veteran Melee players, its just a scrubby mindset and I hate it.
I dont dislike secondary characters, picking secondaries is a legitimate strategy to win. I just hate the common motivation/intent behind it.