>>33975483M-Camerupt's lower half kind of look like a slug, and the speed follows it. And the upper is the obvious volcano.
M-Sharpedo might've had some inspiration to it, but the result was basically "add spikes and call it a Mega". I wasn't a fan of the base design honestly, but they managed to make it worse. Of course, IMO.
Another case of the "spikes" thing:
>>33975588