My opinion on his MU spreads:
60/40
55/45
50/50
55/45
60/40
Let me know if you have any specific questions and I'll elaborate the best that I can. Here are a few things to consider:
A 60:40 match up means that in a Bo5 set, the score would be 3-2. It's not overwhelming, but it is difficult.
Meta Knight's game plan is all about utilizing his amazing ground game and his ground to air game and converting from his grabs and tech chases. Then optimizing punishes and converting into an edge guard. He feels to me like a hybrid of Marth and Sheik, but more Marth, than Sheik.
When playing as Meta Knight, you generally want to stay grounded until you have an opportunity to go into the air. DD back and forth and close space, run in when you have an opportunity and poke with a dtilt. See how your opponent reacts to this and store it as data for your next exchange. Do it again, if they're shielding each time, consider approaching with a boost grab, reading the shield option. Down throw tech chases are great and simple. A missed tech can be covered with a running up smash to put them into the air, where Meta Knight's juggle game comes into play. You can also cover a missed tech with a forward tilt. Up throw and forward throw are great for putting your opponent on a platform where you can harass from underneath, especially if you know they can't shield drop. Up tilts shield stab a lot of characters even with almost full shields.
CC forward tilt is one of the best anti pressure tools in the game and it's the primary reason that Fox goes even with Meta Knight. If Fox approaches with a nair shine, you can CC forward tilt before the shine comes out. You need to DD around drill, however, but what character doesn't? Anyway, pivot forward is good for keeping pressure off of you from approach opponents, especially since the first two hits of tilt cover so much space.
Here is the general thought process behind my placing of most the cast:
Characters that struggle against Meta Knight:
Characters the rely on their ground game: Simply put, Meta Knight has one of the best ground games in the entire cast. He has some of the fastest, most rewarding pokes, amazing dash dance and dash speed, and a fantastic grab game. It's extremely hard to challenge him on the flat ground. Meta Knight is fast enough to punish most characters for even jumping, making it important for them to stay on the ground and deal with his pokes when he is close. There are very few characters who can challenge this. Charizard has a similar archetype, when he has great mobility and pokes, however, his pokes have too much cool down to deal with Meta Knight. Picture you're Charizard, and you get pinned in the corner, Meta Knight is dash dancing around you, what do you do? Maybe jab to try to get pressure off, but if you whiff, Meta Knight will DD right back around and boost grab, dtilt, upsmash, you for even trying. There are some characters that can challenge him on the ground. Specifically Marth and Roy. Roy's dtilt, CC, and dash dance are all amazing. He's good at closing the gap, eating a dtilt of yours and responding with his own dtilt. Also, he has an amazing grab range which can make DDing around him risky. His ground game is very difficult against Meta Knight. If you do get in, you can punish him decently hard, but getting in is very challenging. Marth's dtilt operates differently than Roy's. It hits similarly to Meta Knight's at the tip. It doesn't lead to as many conversions, but it's great for controlling space, especially in conjunction with his grab. Meta Knight and Marth operate almost identically on the ground so it's hard to say that one does it better than the other.
Low Mobility, Defensive Characters: Zelda and Link, for example. Meta Knight's speed in nothing short of amazing. Not only that, but his ability to quickly attack out of a dash makes camping him extremely difficult. Zelda can't safely throw out a Din's Fire because Meta Knight will close the grab in no time and put her up in the air. The same applies to Link. Meta Knight can race almost completely across GHZ by the time Link throws a boomerang. Link and Zelda don't have the greatest mobility to get away from Meta Knight once he puts the pressure on. By throwing a projectile, you're sacrificing your space against him. If you don't have corner escape options like Toon Link does, you're going to eat some damage trying to regain stage control. Snake is the same way. Yes, his grenade is a lot faster, and if he chooses to hold it, he can apply good anti pressure while shielding. But the simple fact is that by sitting in your shield waiting on the grenade to detonate, you're giving Meta Knight ample time to maneuver over to you and start threatening with presence. So you may be asking why Samus is different and I'll get into that in a bit.
Characters with limited disjoint: Characters like Kirby and Falcon have no real way to get into Meta Knight without putting their entire hitbox out there. Because Meta Knight has fast anti pressure and coverage options, more often than not, you'll either trade with these characters or just beat their approaches if spaced properly. It's pretty difficult to circumvent Meta Knight's defenses, so it helps immensely when you have a projectile or some form of disjoint to challenge him with.
Characters that Meta Knight struggles against
Characters than can keep him pinned and restrict his movement or force him into the air: This is basically every losing match up he has. Let's look at Falco for example. Falco's stage control with lasers is arduous to deal with. It forces Meta Knight to either shield or jump, often, neither of which he wants to be doing. Your dash dancing becomes limited and your ground control options are limited. You're forced to close the gap on him and deal with him head on. This isn't always the way that you want to do things. Going into the air is almost always a bad option considering Meta Knight's mediocre aerial mobility. What makes these match ups even harder is when a character has good options out of CC, and even harder if they have good options out of shield. This pretty much defines Samus. She controls space with her missiles. When you close the gap, her tilts are just as threatening as yours, she can upb OoS, and she can CC all of your tilts and respond with strong CC options such as down smash. It comes down to trying to grab her, which, if you do, you don't get much off of since she's not forced to tech. Overall, that's just a very difficult MU.
What to Never do as Meta Knight
Approach a grounded opponent with aerials. Meta Knight does not have strong aerial approach options. He has slow aerial mobility so he won't be able to approach as quickly in the air as he will in the ground. His aerials should be reserved specifically for juggling, edge guarding and reading jump options. They should NOT BE USED TO APPROACH. I can't stress this enough. If your opponent is in the air, it's almost always more beneficial to get underneath them and harass from below with up tilts and up airs than it would be to try and nair them off stage. This doesn't mean you should never use aerials. They're all amazing and have great uses. But when it comes down to neutral exchanges, grounded Meta Knight>aerial Meta Knight.
I didn't proofread this, and I wrote it kind of quickly, so sorry if it's tough to read. Maybe I'll edit it later. If you have any questions let me know.