Yeah ICs is by far the worst MU, but I still feel like it's not the hardest. The MU itself is simple, it just ****ing sucks.
Lucario is tough, but its very doable. This past weekend I played vs Argent Stew in friendlies and we went really even, most of them his win. But we played in bracket and I won the set. I would like to point out that he had just woken up and was really tired the entire weekend. Game 1 he 2 stocked me so I would like to think he wasn't playing that bad, although game 2 I did 3 stock him which I mostly attribute to his tired and an accidental nair offstage on his last stock. Game 3 was really close and went to time on the last stock. That's how I feel the MU should be played. Get the stock lead, and then leave him at 0%. His kill potential in that state is worse than ours, because everything but aura sphere and fair are really avoidable due to our mobility. And even if he kills you, so what? The game is even again, and you know how, he's going to approach you. Of course the main issue with this is getting the first kill, and for this I've found that applying heavy pressure on the ledge really helps, his recovery is incredibly vulnerable to fair and nair so work fairs until he's within nair kill range. Another approach I take is bair/needle camping him on the stage. Stay outside the range of any of his ground approaches(lol grab) and short hop over his aura spheres with your back facing to him and every once in a while use needles to turn around and pelt him(mostly throw needles from far enough away that you can still shield an aura sphere, or when you catch him charging an aura sphere).
Kirby is horrible, I can't help you there.
GnW played well, is really frustrating and difficult. You have to camp him hard and get those punishes in.
Olimar- I have never taken a set off of L_Cancel but I also lost my set to Hilt, so I think it's fairly apparent that Judo is more proficient in the MU than I am. Though I would like to see how Judo vs L_Cancel would turn out. Idk how Judo plays it, but I just rush Olimar down and hope things happen. Also I'm going to start decaying my f-tilt on pikmin. Watch his line up carefully, it will give telegraph his next move slightly. Purple-any color-Blue/White can lead into purple pikmin toss-fair-grab which is like 23%. Don't let the whites get latched onto you, they have amazing DPS, and the same can be said about white pummels. Don't kill the reds because they are his least dangerous pikmin in the MU. They have strong aerials, but average-weak everything else. Blue pikmin are the second least fearsome at high prevents, but I would like to say the most dangerous at low percents. If you get grabbed at a high percent you will get either back or forward thrown, so DI accordingly. Purples do both of thosebwhile also adding in down or upthrow( I can't tell the difference in animation but it's gonna kill you off the top). Purple everything is dangerous, and the ****ers take 15% to kill. Yellow's have extended hitboxes so f-Smash off the stage is a strong humping move he has, it also has a hitboxes behind him when he performed it, and if you get double downsmashes by a purple and yellow it will always send you the opposite direction of one of them(I believe it to be the purple). So if you get the chance perform natural selection on reds, and at high percents let whites live as well. Blues, personally I would kill them because (assuming he has an equal chance at pulling all colors) you have a 2/5 chance of getting something worse, a 2/5 chance of getting something better, and a 1/5 chance of getting something of equal value. Also on certain stages there are different pikmin ratios so watch out for those. I don't know them off the top of my head, but I know he gets more purples on frigate, and more purples and blues on delfino.
Sheik goes to town on pikachu if u dont get chaimgrabbed. I've played 3 pikachus in tournament and 3 stocked them all. They weren't the cream of the crop but even friendlies with Anther we go last stock but majority are his win.
The ICs MU is desolate, having counterpick stages that beat ICs isn't an advantage, because that's generally true for all MUs. Beating ICs on a neutral is a very trying task, but it's not as free a win for ICs as it seems. Sheik can really **** up nana, and even with the sopo chaingrab, beats sopo ( I heard we can GR DACUS solo ICs?). It's definitely an incredibly easy, almost jokeworthy match for ICs but it's not completely impossible.