This stage is extremely short, and should be rather simple for you. There's no screen scrolling, as battle consists of one screen at a time.
You start in a central room, with glowing panels lining the outer side. There are eight of them, and each leads to a boss battle with one of the eight robot masters you've already defeated. They fall just as easily now as they did before.
The best order to tackle them seems to be to start with the robot in the upper left corner, and then work your way around the capsules in a counter-clockwise, inverted arc that ends when you defeat the robot in the upper right capsule.
As you defeat each robot, a large energy capsule will be left behind to restore any damage you may have taken. You should be able to blow through all eight robots with only minimal damage taken. One note: use the Metal Blade when fighting Metal Man (yes, his own weapon) and you will take him down with as little as one hit.
If you've lost all of your lives and have been forced to continue, make sure that you don't use your Crash Bomb attacks. They can prove helpful in the very near future. Otherwise, don't worry about it.
Once you have defeated all eight of the robot masters, a new portal will appear directly overhead, and you can enter it to fight Dr. Wily.
If you've played Mega Man, this attack should be familiar. You're on the left side of the screen, and Dr. Wily is on the right, piloting a giant spacecraft. You should be able to tell where he's sitting, by guessing at the approximate cockpit location. It's pretty obvious. That location is where you should aim your shots.
Whenever I fight him, I just use Metal Blades. Crash Bombs also do some nice damage, if you have them, but they take longer to detonate. Once you have hit his spacecraft enough times in the cockpit, the shield covering it will shatter. You're still not done, however. Instead, you must continue striking the same area.
About halfway through the battle, at the point where the shield falls away, you'll have to work harder to dodge all the projectiles. They bounce along like beach balls, but they hurt a lot more when they connect! If you need to use an energy tank, feel free to do so. It shouldn't take more than one to survive this particular battle.
Amidst the ensuing explosions and bursts of light, Dr. Wily manages to escape yet again, in his private pod, and the castle's secret final level appears.
NEXT: Stage Six