Matador, do you expect to beat the good King Dedede players any better with Meta Knight than you do with Ice Climbers? Honestly? You're going to lose with both of them. You can't just pick up a random character, including Meta Knight, and expect to beat people who are actually good with certain characters. You might as well just stick with Mario, lose anyway, and save yourself the grief. If you want to seriously learn a character, it's not like Meta Knight is even less work than most characters, including Ice Climbers. Ice Climbers are more about being technical than anything anyway; you have an instantly tournament viable secondary even if you are pretty bad as long as you literally always kill off an appropriate grab (you still won't beat anyone good, but you'll do better than you will with a scrubby Meta Knight).
Honestly, if you really think Meta Knight is that good and so overpowered (he isn't), just main him and get it over with. The truth is that he has large and exploitable weaknesses just like the entire rest of the cast, and I'm extremely doubtful at best of the claim that he has no bad matchups (Snake uses utilt?). The culture that hypes Meta Knight so much is a bit ridiculous, but that's getting off topic...
Do consider this. You really don't have an advantage in most matchups if you secondary Meta Knight for a simple reason. Against other high tier characters, Meta Knight has a pretty small advantage in general (usually 55-45 or 60-40). Now, assume he is actually your secondary, and assume they are using their main. You have an abstract matchup advantage of 55-45 (very small), they are using their main (their best character), and you are using your secondary (a character you are probably noticably worse with than your main). Assume equal overall player skill; who wins? I'd bet my money on the guy using his main. I honestly can't think of ever seeing anyone go Meta Knight if they weren't already very serious Meta Knight users and do anything but lose badly; it's just plain not a good way to win.
Also, I'd like to point out that not many characters who are generally good have really awful matchups (what is it; DK, Wolf, Fox, Ness?). If you want to use those select characters, secondaries really do make sense. Otherwise, you're probably already low tier and looking at awful matchups you want to use secondaries to avoid. That's a sign that either you already have some killer strategy worked out on your character use (far beyond what simple advice could help with) or that you are not selecting your characters for the purpose of doing as well as possible. That's fine (you can pick characters for whatever reason you want), but if that's the case, grabbing a very high tier secondary (like Meta Knight) just to win seems very silly and inconsistent with your previous standards. Of course, low tier isn't blanket like that; lots of low tier characters are not low tier for having hard counters. Pokemon Trainer is probably a decently uncontroversial character to be in low tier, and he has zero awful matchups. Secondaries don't help him very much at all.
I didn't mean to say previously that secondaries are always a bad strategy, but I do think mot players would do better without them. Most players do main a character who is high tier and has no hard counters, and I do think it makes sense to talk to them. If you main Diddy Kong, do you really need a secondary? I mean, maybe having one just really suits you personally, but Diddy Kong can do it alone, and you might benefit from the focus if you did as such.