The final Doc Robot stage you should attempt is quite difficult, but nothing you won't be able to handle by now. Just be prepared for a challenging Rush Jet segment a little over halfway through.
Before you get there, though, you'll have the first third or so of the level to deal with. Begin by heading right, past a series of porcupine robots. Most of them are at ground level, and thus easily tended to with a barrage of arm cannon shots. Beyond those, you'll find a ladder leading down to a series of spike rooms.
This portion should be familiar to you from the previous play through the area, but it's still enough to give a challenge. Work hard to avoid letting them hit you, and remember to slide as the first one is most of the way through receding to avoid the second spike in most groups.
Beyond the rooms of spikes, there's a ladder leading up to a room with one of the red-capped springs. Shadow blades are handy here, as they can easily turn the robot to scrap metal and block any missiles that may be headed your way. Once that's tended to, go ahead and climb the ladder on the screen's left side.
At the top of this ladder, use the Rush Coil to reach the next ladder, and climb it to find the gate that leads to the area's first encounter with Doc Robot.
Doc Robot - Air Man
The weapon of choice for this battle is the spark shot. However, you won't normally be able to get in a clear shot because Doc Robot sends out gusts of air in various formations.
What you'll need to do is jump over or slide under various air gusts, then counter with the spark shot. It's going to take a fair number of hits, especially if you fire in rapid succession, but once you get an opening Doc Robot will go down swiftly.
Now for the last leg of your journey through this stage. It's the tough part, too, so buckle up.
From the encounter with Doc Robot, walk just to the right and you'll find yourself staring out at a vast, empty space. Switch to the Rush Jet and start the trek across. The whole time, you'll be pestered by descending parachutes and dragonfly enemies.
For me, the best technique was to spend most of the time crossing the gap at about halfway up the screen. I mostly tended toward the high side, so that the parachutes ahead of me would drop below me quite quickly. However, the dragonflies mean that you have to change elevation frequently to avoid excessive damage. Not only that, but the Rush Jet only has so much energy. Because of that, you'll have to make pit stops at certain ledges to refill its meter.
It's a challenge, but you should be able to reach the ladder at the other side of the pit in pretty good shape. Once you do, climb the ladder and you'll find a special item refill, which you should use to recharge your jet's energy. Now use the jet again and ride it up to the ladder at the upper left side of the screen.
Climb the ladder to its top, then switch to the shadow blade, which you'll want equipped right up to the moment you find the gate that leads to Doc Robot.
As you press to the right now, you'll encounter a lot of hardhat enemies of various size. First you will run into a monstrous machine that rises from the ground. It is vulnerable only where you see the red cross, so be ready to move in quick and toss a flurry of shadow blades in that general vicinity. The weapon also does a fine job of taking out any miniature hardhat foes that race toward you at ground level.
Past the first giant hardhat, you'll find some more of the miniature fellows. They glide around in the air, somehow, but still succumb quite easily to shots from the shadow blade. Also, there are more of the domed cannons. Again, you'll be amazed by how effectively shadow blades work here. They should take you right through to a second one of the giant hardhat machines.
Beyond the second of the hardhats, it's only a short jaunt to the gate that leads to the final Doc Robot encounter.
Doc Robot - Crash Man
Remember this guy from Mega Man 2? This time around, you don't have the air cyclone on your side. Instead, you'll have to use the hard knuckle.
Doc Robot will hop around the screen a lot, but for me the simplest strategy was just to stay at the very lower left of the screen and fire a series of hard knuckle shots. Since he moves around so much and the knuckle attack itself is quite slow-paced, Doc Robot did himself in while I supplied only four or five shots with the hard knuckle. This is quite possibly the simplest of the Doc Robot encounters.
At last, you've done it. The Doc Robot stages were no match for your skillful abilities, and a new hazard will appear on the screen where formerly Mega Man's head rested.
A-1 (blue), A-3 (blue), B-2 (blue), B-4 (red), B-5 (blue), D-3 (blue), F-4 (blue)
NEXT: Break Man