I really should build an army of those dog-horses...
... Darnit... You got past my Fortress Bosses!? FINE TREMBLE IN FEAR AT MY LATEST WILY II MACHINE

(Click to see it in full-size)
This is the first form of the Wily II Machine 8 that Megaman faces. A
"gift" from a certain fox-boy, this machine resembles a giant robot spider. Instead of bullet hell, it's spike hell.
During this first phase, the machine will be crawling up and down the walls, attempting to stay out of reach from Megaman's attacks. Once it stops, the following attacks will occur: Firstly, the claw cannons will rain down energy shots with very slight homing, after which, the turrents will fire off cannon balls that bounce on the ground, next, the 4 legs will straighten out, and spin about the body-leg core (just like how the spider midboss in Rospark's stage does it in ZXA), then one of the fore-legs will try to stab Megaman (Which is instant-KO), lastly, the machine will attempt to stab Megaman with the 3 spikes under the skull (Which is also instant-KO). After this cycle, the machine will begin crawling along the walls again.
It seems there is a way to stop the legs from spinning... Snail Roller...
It's like this, given Snail Roller can bowl over enemies, that power can be used to push back the legs when the spinning starts, overloading the body-leg core.

(Click to see it in full-size)
This is the second form of the Wily II Machine 8, after Megaman destroys the body-legs core with the help of Snail Roller. With the core destroyed, it reveals DWII in the cockpit. Without the legs to support the machine, the machine bounces erratically around the room, with the help of the 3 propellers.
While bouncing around the room, the claw cannons will still rain down energy shots, and the turrents will still fire bouncing cannon balls to further the chaos.
With the propellers gone, maybe the bouncing will stop... Engine Slicer...
Engine Slicer can bounce around the room as well, and be able to hit the propellers.

(Click to see it in full-size)
DWII doesn't really believe in capsule battles, although this does resemble a capsule. With the destruction of the Wily II Machine 8 by the hands of Megaman using Engine Slicer, this is what remains of the Wily II Machine 8.
The claw cannons have retracted back into the capsule, and now fires spread shots. The turrents still fire bouncing cannon balls, and the capsule will still try to stab Megaman with the 3 bottom spikes.
Hmm... Tends to stay in the air... Up Planet Elements...
... You're expecting an explanation? Seriously?