Right
Easiest:
MM1: GutsMan! DUNN DUNNNNNNNN
MM2: CrashMan. Tedious, but very predictable
MM3: TopMan.
MM4: rofl ToadMan
MM5: StarMan
MM6: WindMan, pretty hard to get hit by him
MM7: JunkMan is fairly easy I guess
MM8: What
MM9: SplashWoman. GalaxyMan can at least randomly decide to fly towards me. Splash always does the same thing
MM10: BladeMan, if you know how. There is a way to beat him without even taking the risk of getting hit
Hardest:
MM1: ElecMan. I don't think I ever beat him without his weakness
MM2: Goddamn QuickMan.
MM3: ShadowMan. Too random
MM4: Either DrillMan or PharaonMan, can't decide
MM5: ChargeMan. When I decided to beat the boss rush using only the M. Buster, he was giving me the most trouble
MM6: TomahawkMan.
MM7: SlashMan. Why did they have to give him the attack where he starts throwing
Bob the red stuff at you?
MM8: What
MM9: MagmaMan. While I have a pattern that I could use to kill him with no damage, it requires good reflexes. And sometimes I just lose focus and get hit with each jump he makes
MM10: NitroMan.