Mega Man 4/Pharaoh Man
It's off to the desert to fight the next one of Dr. Cossack's creations. The first section features sinking quicksand and assorted foes. Fight your way through, and don't let the sand eat you alive. When you reach the pit, DO NOT fall in. Use the Rush Coil to jump over it, and go one screen further to the right. You'll find the Balloon item here, and skip a pretty good-sized chunk of the stage!
The rest of the stage is pretty standard run-and-fire stuff. Just keep bringing the pain and you'll eventually reach the boss lair.
Pharaoh Man is one tough guy. Seems like most robot masters have speed but lack power, or vice versa. This guy has the best of both worlds, which guarantees he will not be an easy boss. But if you've got his weakness, the Flash Stopper, he can be turned into a sitting duck. Activate it as soon as you enter his lair, stand before him, and rapid fire. Just keep rapid firing, and you'll automatically reactivate it each time it runs out. Don't attempt to challenge this guy without the Flash Stopper, I can pretty much guarantee you won't win.