Do you think it's fair that Mario gets at least 3 free shots at going Metal in each 4-stock match? Whenever you fight Mario, you can count on at least half a minute of that match being you playing Keep Away from Metal Mario. This is a huge assist for Mario that he doesn't even need against most characters.
Waiting for Metal Mario to make a mistake... That works if you have a chaingrab or attacks with high power and priority. But plenty of characters have no viable option against him if Mario's playing safely. No other character has such a feature, that basically says "it's your turn to attack now, your opponent can't do anything but try to avoid you!" multiple times per match.
Too many matches I've played against a good Mario were ruined by the Metal Cap. It would be a close, even match until Mario started abusing the Cap, giving him the advantage he didn't even need. Whenever Mario gets a KO, he puts on that Cap. I respawn, and because I know I can't get to him in time to stop him from going Metal most of the time, I stay on the respawn platform as long as possible, and play Keep Away once it vanishes, until Mario reverts to normal.
This STALLS THE MATCH. Whenever I fight a good Metal Mario, I'm encouraged to stop being aggressive and run away for ~10 seconds after each time I'm KO'ed. Who thinks this is a good game mechanic? The Metal Cap harms the balance, pace, and flow of the game much more than it helps it. Minus would be better without it, or at least a more heavily nerfed form of it. As-is, Mario's Metal Cap is the most needlessly powerful and game-changing taunt in the game. It's better than Lucario's ultra taunt now, because Mario gets a free shot at using it after every KO, and there's no reason not to go Metal unless your opponent can chaingrab or lock you in place. IIRC, the Metal Cap activates faster than Lucario's ultra taunt too, and of course Mario doesn't have to hurt himself to use it.
I hate fighting Marios who abuse the Metal Cap. Mario is great enough without it. This taunt might as well turn Mario into Super Baby Mario instead, because all it's doing is babying the Mario player. You scored a KO? Woo, have 12 seconds of near invincibility! Your opponent will just have to deal with it. Going Metal is equivalent to saying "I need help, this is too hard, waaa" or "I wanna be cheap and stall the match, whee" IMO.
If every character's best option against Metal Mario is to avoid him, why is it kept in the game?!