I now change my vote to none, after the 2 100% speed runs. Practice with Robo Ridley and you can easily make him your rid-lay, even on 100%. Get it? be-yotch = rid-lay? Nobody's laughing...
I think that the hardest boss on a normal run was Mother Brain. Those ring-things and "bullets" never stop shooting at you. They keep knocking me off the platforms and into the lava, making mother brain close her eye.
I am doing a normal difficulty 15% run right now, and I can't beat ridley. I run out of missles and then he grabs me and kills me before i can shake loose (the damage from touching him + from those tiny fire balls he shoots). I can't imagine how hard Mother brain will be.
Mother Brain. Killing her on low % without Screw Attack is just retarded :(. Though I never actually did a hard Mecha Ridley (grabbed 6 Super Missiles so he's a pansy)
Mother Brain is so hard on 15%!! Even harder than Ridley, who took me about a week to beat. It didn't take me as long to beat her though, thanks to the morph ball technique.
Since I really only do 100% and Any% runs, most of the bosses are pretty easy. (With some experience, 100% Meta Ridley is a chump.) I voted for "Samus-in-a-ball" because that fight is horribly annoying, especially when you have to hit the ball the fourth time while dodging lightning bolts.
Mother Brain forsure. Kraid was a little harder then I exspected, died once the first time playing the game. Ridley was the same old shoot till one of you die, maybe even a little easier then before. Meta Ridleywasn't bad, but he was still easy. Mother Brain tho0ugh, she was actually hard.
I played Zero Mission on hard, with 100%, and Mecha Ridley wasn't even hard. Took me 3 tries.
I think none of the bosses are hard... although on my speed run, fighting Ridley was quite a chore. I found out a good strat though.. when he comes down, blast him with missiles, and then when he's done his fireballs, jump back and give him hell. For the rest, just try to get under him. Simple.
I can't even imagine the difficulty of a 10% hard run... mother brain would be death.
I found Ridley to be the hardest because whenever I was under him, 9/10 times when I was under him he either landed on me and shot the smaller fire balls, whip me with his tail, or bounced around on his tail. If I was on 9% or 10% runs though, he'd never do any of that, which made him a pushover.
For Mother Brain, I always stood right in front of her eye and unloaded super missiles and normal missiles at her. If she tried her mind blast, I just morphed into a ball to avoid it. On a low percent runs she was a bit harder because of the turrets when you try to jump over the mind blast.
Kraid took two seconds with three super missiles and Mecha Ridley took six super missiles...easy. Mecha Ridley is a pain on low percent though.
I know for a fact the crocomire is a pushover, well not quite as much of a pushover as the SM one(get it?), but still rather easy. Of course I did have the plasma beam at the time.
Crocomire killed me the first two times I faced him o_o... and I certainly didn't have the Plasma Beam. He was easy when I figured out what to do though.
i chose samus in a ball although that seems to be the least popular. just when i shoot it turns back to samus so i kill my self (no mother brain tricks either) 8) 8)
I always thought the Chozo Ghost thing was more annoying than hard. It's too random, and if you shoot at the wrong time you'll hurt yourself. That ghost sucks.
Kraid was a snap most of the time, unless you ran out of missiles. Ridley was pretty hard on Hard, because his tail did devastating damage, but was manageable. Mother Brain was SO F*CKING HARD every time until I read that MB boss trick, then she was really easy. Samus-in-a-Ball/Chozo Ghost/Ruins Test was frustrating because it was hard to get to a good shooting angle. Robot Ridley/Ridley Robot/Mecha Ridley/Metal Ridley was really easy until I fought him on 100% hard. Then he was a BITCH.