I agree with most of this post, but I wouldn't say any disadvantaged matchup, a 6-4 matchup is still very winnable by either side. I'm all for pocket characters to cover the odd 7-3 or 8-2 MU ( idk if anyone is calling any MU's 8-2 yet, though I could see it in this game ) otherwise I'd almost always say it's better to learn your slightly out of favor matchups with your main, unless you really have time to drop into learning a pocket character or are planning on just using him for one MU. Also tbh trying to put MU numbers on things is hard right now, they're never going to be set in stone but as this early there's still a ton to find with almost every character.Considering that the strategical point of secondaries is to cover the disadvantageous matchups of your main, I would say that the only characters who don't need secondaries alongside them are ones who either have no bad matchups or whose only bad matchups are characters who have no bad matchups themselves. It's too early to say if there are any of those, but someone like Ness definitely isn't one of them because, while he's really good, I could see his recovery easily abused by characters such as Rosalina, Villager or anyone with a good counter. It's also hard to see Mega Man not getting some polarized matchups with his style of play. I do agree the others are pretty versatile though, but as said I think whether or not you need secondaries isn't about that in the end.
MU numbers are always weird to me anyway, when can you really say someone is playing X to the highest level? Half the characters in this game won't see a world class player main them anyway so it's hard to say we will ever see them at the highest level.
For instance I see a ton of charizard is garbage tier posts, do we have a top flight player repping charizard? If we do I feel stupid but I think out of all the heavies in this game he and Gannon come the closest to being a viable competitive pick, Gannon because rage and a punish or good read means death. Charizard because his recovery options are pretty damn good, he can punish things at an absurd distance with a move that can KO. He has good ability to gimp, like really good ability. I think people dislike him so much because optimally playing him is either bait and punish or just approaching with the same thing over and over, but he hits like a truck and if played smart can control space like crazy. Oh and disjointed moves are sweet sweet candy.