You're now in what the map indicates is the last stage. You don't believe that, though, do you? From where you begin, jump left and collect an energy tank. You can also refill your special weapons, so be sure to fill up on the ring and on any Balloon energy you my need, in that order.
When you drop into the next room, you'll find yourself greeted by the red-armored enemies, who zip merrily about the ledges in an attempt to drain your life energy. The ring shot will make quick work of them, and you can collect small energy capsules from the recess in the wall if necessary.
From there, drop down the pit to your right and veer left as you do so. You'll land on a new ledge with special weapon refills. With those collected, drop down the pit to your right yet again.
Once you land, be prepared to take out the two enemies in this area. Each will fall either to three quick arm cannon shots, or a charged mega buster blast. They're the top-like enemies. Drop down the pit past them, to the left.
The next room contains another of the red-armored enemies, which guards a gate leading to this area's boss encounter. Pass through it.
The Robot Masters
Through the gate is a short hall and a transporter device that leads to a new room. Drop down the shaft to your right. You'll take a long fall into a new room filled with transporters. The chart below indicates which robot is where:
  1 - Drill Man 6 - Dust Man
2 - Bright Man 7 - Ring Man
  3 - Skull Man 8 - Pharaoh Man
4 - Dive Man
 5 - Toad Man
When you defeat the eight robots, a new transporter will appear at the top center of the screen. Enter it to fight the next boss.
This new boss is a more challenging foe than the eight robot masters. It will descend upon the screen as its life meter fills. Quickly power up your mega buster shot, then move over to the front of the machine, just below its gaping mouth as it moves up and down.
While you are positioned thus, each of the purple energy balls the machine spews will go over your head. You can power up your mega buster shots at your leisure, and jump to fire them into its mouth between each triple set of energy balls.
When the enemy's life meter is emptied, the skull face will fall away and you will see Dr. Wily, controlling the machine from his pod.
You're now at the tough part of the battle. The pod will fire an almost endless stream of shots from this point, and you must slide under it so that the shots can't hit you. There, power up your mega buster shots. When you're ready, rush out left. The next shot that heads toward where you stand on the ground is your cue to jump into the air and hit the portion of the craft just below Wily's bubble with your mega buster. This will do a good amount of damage.
Once you've struck, slide back under the skull machine to power up your shot again. Keep repeating this until you deplete the entire life meter. Dr. Wily will escape in his pod. There's one more stage to go.
NEXT: Stage Four