Sadly, I cannot hit Wily's Castle with Metal Blade. Or at least, it doesn't do anything.

i actually only used the metal blade to beat woodman and never again when i played MM2

I used it for Bubble Man and a couple of times near the end, plus in Wily's Castle so I could get more crash bombs.

That's the main problem I have with 2 - you have the OP Metal Blades for the whole game until you get to one of the worst designed bosses in history that requires every crash bomb you have - miss one and you gotta go find more, and it involves use of item-1. Just... bad.

As bad as that boss was the reason I don't really like 2 is that the difficulty is so inconsistent. I don't mind hard games but the parts that are easy are too easy and the hard parts you generally have to know about beforehand and they come so out of nowhere. And like I said before, all the weapons feel pointless after you get metal blade.

Bubble Man is my favorite stage ever though.

^the only megaman 2 stage that wasn't annoying at all

quick man has the best music anyway. that's a Science Fact

really though, Mega Man being in SSB4 means the soundtrack is the part of the game I want the most

I'm attempting to 'Nuzlocke' mega man 3. Feel free to join me or try the other Mega man games.
Rules:
-after you've beaten one robot master, you CANNOT use the buster. you are allowed to shoot the rush marine canon.
-you can die, but if you game over, that's it and you have to restart.
-do the robot masters in whatever order you want, but remember as soon as you have a special weapon, you have to use it, so choose your first stage carefully.

I'm not even sure if its possible, but I've beaten 3 bosses so far without too much hassle, and I'm enjoying it a lot.

TOP SPIN

I considered top spin, but I'm not sure I could make it through shadow mans stage with enough ammo left over to actually beat shadow man
current attempt started with needle canon and that's going pretty well

romhack all the NES games and make every weapon Metal Blade

Are you allowed to use any weapon? If so, might as well go for Shadow first - Shadow Blades are pretty much the equivilent of Metal Blades. You also get a free Rush Marine out of it. That's assuming you can beat Shadow Man buster-only... After that, the game is straight forward.

You could probably do something similar with 4's Dive Missile, 5's Gyro Attack, 6's Yamato Spear, 9's Laser Trident, 10's Triple Blade. The key is just to find the buster replacement weapon.

EDIT: You might have some trouble on the Rush Jet sections without being able to shoot, but that shouldn't be too much of a problem. It's definitely doable.

I find that the Needle Canon is the better buster replacement than the Shadow Blade, it can be shot faster and it's awesome for taking out the flatter enemies like the frogs. Also I personally find Needle Man easier to beat with the buster than Shadow Man. The other thing is that Top Man's weapon is so damn useful on Shadow Man's stage overall (not just for the boss fight) that it's a waste to not take advantage of that on my route.