The last of the initial eight robots resides in a fairly simple level made remarkable only because of the huge spikes and needles found throughout.
Begin by heading to the right, where you'll encounter porcupine-like robots. They will fire two bursts of needles before rolling into invulnerable balls and finding a new place from which to attack. Avoid the spikes, dodge the rolling foes, and move onward. Avoidance truly seems the best policy.
Past the porcupines is a ladder leading down to another straight stretch. Take the top path as you head right (the bottom one is a pointless dead end). You'll soon see a golden dome atop a pillar of the same color. The dome slides open to reveal a cannon, which you should pelt with shots from your arm cannon. This machine sends out red balls that do quite a bit of damage if they connect, so try not to allow the machine time to make its move.
Past this first dome cannon, you'll find two more, as well as an assortment of hardhat enemies. Nothing here should be terribly taxing, but the red balls will definitely bite into your health if you allow yourself to be careless.
When you reach the end of this segment, there's a ladder that leads down to the stage's checkpoint. That's right; you're already halfway through. Climb the ladder down to the lower ledge, and head right.
In this portion of the stage, you'll want to be careful. Reddish spikes will protrude from the ceiling, then recede, then protrude again in an endless loop. You'll want to slide through as the needles start to recede, so that they don't have time to come back out and hit you before you've passed through. First there's a single needle, then a set of two, and finally a group of three, but the strategy is the same each time.
Once you're passed the row of three spikes, you'll find a wide, bottomless gap greeting you. There are three gold-colored ledges suspended over this pit. Hop out onto the first, and watch the air above the second. There's another spike there. Wait until it starts to recede, then quickly hop up and from there, slide over to the third of the ledges. The spike should just miss you, and you can now safely climb the ladder leading into the next room.
Here, you'll be greeted by another porcupine. Carefully avoid it. The most likely set of events here is that the porcupine will survive long enough to roll down to your level. Hop over it and to the ledge it just left, then turn around and use some well-time search snake shots to put it out of commission. With the screen clear, you should next use the Rush Coil ability to hop up to the outcropping in the screen's upper right corner, where there's an energy tank. Next climb the ladder at the screen's upper left side.
You're now in a room with two of the projectile-throwing enemies you've encountered several times thus far. Fortunately, they're easily dispatched if you climb not quite to the top of the ladder and fire from that safety point. Continuing upward using the ladder to the upper left side of that screen, you'll find yourself approached by one of the giant stomping robots.
At this point, your life meter is likely all but empty, so the strategy I advise is again a careful retreat. Slide under the monstrous machine when it leaps, then keep moving quickly to the right and through the gate that leads to the eighth robot master.
NEXT: Doc Robot Stages