Toughest Robot Master in Each Game?

[Korby]

His is especially volatile, as pretty much no one(but Enker or Wily) can block it.

[KillerChair]

MM1: None... Exept when i do buster only, Then Elecman.
MM2: Same as above. NONE!
MM3: Also none... Exept when you think the doc robots count. Then doc robot Quickman buster only
MM4: Toadman! (lolz...) Nah not really any tough ones here.
MM5: All too easy.
MM6: Maybe Tomahawk man... But also not really tough or anything.
MM7: I can almost play the game blindfolded -.-
MM8: Swordman
MM&B: Dynamoman. (specially when playing megaman and buster only'ing    )
MM9: Magmaman
MM10: Blademan or Strikeman.

[Kapus]

Blade Man is the easiest robot master since Toad Man.

[Myroc]

MM1: All the Robot Masters were pushovers with their weaknesses. I mean, most of them die in two-three hits. Discounting weaknesses, I'd have to say Ice Man. It's such a simple pattern, yet I fail to dodge it all the time. It's also a three-hit kill, like Elec Man's attacks.

MM2: Wood Man. Again, a lot more bearable with his weakness Atomic Fire (or Metal Blade, if you're so inclined), but seriously. I cannot buster-only this guy. His attacks are hard to dodge, and I cannot keep up to the damage he gets in on me with just the buster.

MM3: Snake Man. I've always had some trouble jumping over him when he decides to run into your part of the battlefield.

MM4: Dive Man. I can dodge his dash attacks rather well, but he fucks up my timing when he decides to shoot the dive missile at me (which also eats through my shield).

MM5: Charge Man. This isn't really because he's hard, but he's the least easiest boss. Seriously, they're all pushovers in this game, weakness or not.

MM6: Tomahawk Man. I hate it when he jumps just long enough to trap you in a corner but not long enough so you have time to slide under him.

MM7: Fuck you Burst Man. No one likes you and your bubbles that you just BARELY have time to break out of with the buster. And that's assuming you're trapped in one of them on the ground. If you fall from the air after bursting out of one into a second, you're doomed to a spiky ceilingy death. This is the only boss where just having the weakness wasn't enough for me, I'd need Junk Shield just to break out of those goddamn bubbles.

MM8: This is going from RM8FC because I haven't played the normal one for Playstation/Sega Saturn beyond the intro stage. I'd probably have to say Sword Man, but they were all pretty easy, atleast with their weaknesses. I haven't tried to Buster only all of them, so I might be a bit biased with this one. Ah well.

MM&B: Burner Man. Not Dynamo Man, although he was a douche as well. I actually found it easier to use Copy Vision on Dynamo Man than it was to use Ice Wall on Burner Man, since I for some reason had difficulty to get him in the "trapped" stance. Otherwise he'd just burn through it with wave burner. This proved to be annoying.

MM9: Concrete Man. Was a bitch to fight even WITH Laser Trident.

(I have not played MM10, so I can't give an opinion on that.)

Edit: You know, in lack of MM10, I'll add MMV instead. They were KIND OF easy in MMV, but the one that annoys me the most is Mercury. Not because he's hard, but screw up, and you can lose anything from weapon energy to p-chips to ENERGY TANKS. Or even goddamn MYSTERY TANKS. That ALONE makes him my first target when I play this game, since I don't want to lose my precious E-Tanks to him.

[LlamaHombre]

MM1: Ice Man (Hard stage followed by hard boss.)
MM2: Air Man (I SAID IT.)
MM3: Needle Man (In the cell phone version, you can't shoot him unless he's in the air. >_>)
MM4: Drill Man (GTFO OF THE GROUND)
MM5: Gravity Man (More or less the stage, but...)
MM6: Tomahawk Man (Hair.)
MM7: Freeze Man (...)
MM7FC: BURSTMAN FEOBAOBOBA
MM8: Frost Man (JUMP JUMP SLIDE SLIDE)
MM8FC: Grenade Man (FUUUUUUUUUUUUU-)
MM9: Splash Woman (Those frikking platforms kill me, I swear.)
MM10: SOLARMAN GOBOABOVBA

MMI: Cut Man (Uhuh.)
MMII: Magnet Man (Low jumps)
MMIII: Haven't played too much, so far Snake Man.

[easyaspi]

MM1: Elec Man
Not necessarily his battle (Trolling Cutter, 3 hits), but his stage. Watchers, cheap jumps, and Yoku blocks. *shiver*
MM2: Quick Man
This spasmodic, rage-inducing boomerang-spammer can MESS YOU UP. The sound of the force beams gives me nightmares.
MM3: Needle Man
No pattern, spammer, likes to corner you. 'Nuff said.
MM4: Bright Man
Not too bad if you know his secret (hint: use a charge shot at 15, 19, and 23 damage), but he still spams and has the habit of jumping on top of you.
MM5: Crystal Man
I know, some of you are laughing, but his Crystal Eye can get really tough to dodge sometines, if it rebounds right.
MM6: Yamato Man
I don't know why I have so much trouble with him, but he's tough to dodge, even with an easy pattern.
MM7: Freeze Man
Without Junk Shield, he's a spaz, and, even though he has a predictable pattern, all of his attacks are really big.
MM8: Grenade Man
His stage is aggravating, his miniboss is annoying, and I refuse to say hello to his cute bombs. MASOCHIST.
MM&B: Astro Man
Even with Magic Card, his Copy Vision can get tough to dodge, especially with the enemies he spawns.
MM9: Concrete Man
He can freeze you, dash into you, and hurts like a lemon wrapped around a brick hitting your brain. How could someone so bulky be so AGILE?!?
MM10: Chill Man
Spaz, cheap shots, and hard to hit with his weakness. Also, he has a stage that is absolutely LETHAL.

Bonus Content:
Rockman No Constancy: Quick Man
His force beams are worse than the originals, especially with ice floors, he can turn himself into flames, and he's even faster.
Mega Man: Powered Up: Bomb Man
Two Words: Critical Attack. It's so hard to dodge and hurts terribly.
MM: TWW: Cut Man
Much worse than the other version, since he only takes 1 bar of damage from the buster this time.
MM: DWR: Cut Man
Spazzier, Trolling Cutter hurts much worse, and his weakness takes away only 2 hp.
MM: DWR2: Needle Man
Now he's weak to Top Spin, and that's even worse.
MM: DWR3: Dust Man
His stage has aggravating jumps, though he himself's a cakewalk.

[-FiniteZero-]

MM9: Concrete Man
He can freeze you, dash into you, and hurts like a lemon wrapped around a brick hitting your brain. How could someone so bulky be so AGILE?!?

So, a Pan-Galactic Gargle Blaster?

Anyways, more:
MM1: None, They be too easy.
MM2: None, see 1.
MM3: None, see 1.
MM4: None, see 1.
MM5: None, see 1.
MM6: None, see 1.
MM7: Turbo Man. Damn pattern (mainly talking about FC version).
MM8: None.
MM9: Haven't played in a while, but if I had to guess... Magma Man. Buster only. With his weakness, he's easy.
MM10: Haven't played yet.
MM11: Woah, I'm getting ahead of myself.
MM12: Seriously, I need to stop.
MM13: None, see 1.

[Kapus]

Given that 90% of the robot masters in the series are cakewalks with their weakness, I think people should be basing their posts off of their buster only experience.

[Mr. X]

I don't think so.  There are robot masters who can be annoying even with their weaknesses, like Concrete Man.

[Nuy]

Given that 90% of the robot masters in the series are cakewalks with their weakness, I think people should be basing their posts off of their buster only experience.

Buster only still doesn't affect Mega Man 1.
Mega Man 1 has the easiest robot masters ever.

[TrueTenguMan]

Why does everyone find Dive Man so hard?

Cause Dive Man is a spammer... and he deals ridiculous amounts of damage...

[ice]

MM1: Broken 3 hit kill elecman
MM2: woodman (ALWAYS played on difficult)
MM3: Hardman
MM4: Ringman's undodgeable rings (Diveman is only hard for me if I use his weakness, its easier buster only)
MM5: Napalm
MM6: Blizzardman
MM7: Turboman or shademan
MM8: Tenguman
MM&B: The mother of all hard megaman games I'd say Astroman, Went from fail teir to god teir, He's already hard to hit and dodge but its also hard to use his weakness on him (God forbid if Inafune would of let him keep astro crash). Honorable mention to Dio Brando Burnerman, he moves around too much shattering ice wall, and he has a HUGE arsonal of attacks

[BiscuitSlash]

Why does everyone hate concreteman? Really, once you kept on trying with the buster his pattern is easy. Still, he's my favorite of the game

MM1: Elecman or Iceman - Powerful attacks (But I know a trick to easily no damage - buster only fireman. It actually worked for me!)
MM2: Hmmm....Quickman or Woodman - I don't hate quickman because he gives an epic fight, but those leaves....so hard to dodge!)
MM3: Needle/Shadow/Hard - Needleman and Shadowman are both ninjas that you need very fast reaction too and hardman is hard
MM4: Diveman or ringman - reasons already said in previous posts
MM5: Not sure, but chargeman gave me quite a bit of trouble
MM6: Tomahawkman, but he's not so hard. Fun fight
MM9: Plugman - you'd probably know why
MM10: Solarman - Haven't figured out that technique yet. (Can't beat this guy buster only on normal!)

[Atticus]

MM1: None are that hard, I'd say Iceman.
MM2: That fast little sonofabitch Quick man.
MM3: Shadow man, unpredictable asshole.
MM4: None are that hard, maybe Pharaoh man
MM7: Slash Man, damn fruit.
MM8fc: The new Sword man. ASDFGHJKLFIRESLASH
MM9: Buster only, Hornet Man.
MM10: Commando Man

[TrueTenguMan]

MM8: Tenguman

Don't be trolling me man...