Mega Man 4/Dust Man
Dust Man's stage is pretty straightforward, but there are some threats you need to be aware of, mainly the smashing ceilings. When you find these things, blast away the chunks of debris to clear a path through. Use a mixture of running, sliding, and blasting to get through these tough spots. The rest of the level should be nothing you can't handle.
Equip the Ring Boomerang before you go into Dust Man's lair. The guy has two main methods of attack - shooting chunks of dust at you (which then explode into smaller chunks), and trying to suck you in with his head vacuum. His pattern is predictable and he doesn't throw any major surprises your way. Just make good use of that Ring Boomerang, and he should fall quickly.