Brawl also doesn't have WD out of shield options and many of the moves in that game work differently from similar moves in melee. It's a slower game in general and he can get away with stuff there that doesn't work in melee's engine.
Some characters combo Jigglypuff in this game, so I don't see how Metaknight would be uncomboable. For example, I think his match up against Falco would be relatively even if not in Falco's favor. (Unless you're factoring in the complete lack of hitstun in Brawl and low shieldstun, in which case we're putting Melee characters in Brawl [not the other way around] and he would competely wreck them.)
This discussion is kind of pointless anyway since Metaknight isn't in Melee and will never be in Melee.
Brawl actually has the same hitstun as Melee, but has it explicitly coded in to the game that Brawl airdodges can cancel hitstun on frame 13 and attacks can cancel hitstun on frame 25.
If you kept Metaknight identical to Brawl, he would be like this. His airdodge breaks hitstun on frame 13 regardless of how much hitstun has been applied by the move. This would give him a huge advantage on any Melee character.
Plus he'd have the low fall speed of Brawl making him hard to combo.
Yeah, sure, Fox has much more movement options, but MK has
better options. He doesn't
need to wavedash out of shield when he can nair OOS instantly without landing lag. He has Marth-like range via ftilt and dtilt and aerials that autocancel with almost no landing lag. He can aircamp Fox and Fox can't do too much and can basically zero death Fox out of a hit very easily.
Even if all of the different movement options gives Fox a slight edge in neutral, this will be the one character he CAN'T zero death in the hands of an expert character. Fox will take SO much more damage out of a hit than he will give out.
And that's assuming MK doesn't get all of his global Brawl features, like super-Smash-DI.
If we put him in Melee physics, we basically have a souped-up PM MK which still craps all over Fox.
