According to an interview with Ken Sugimori, Deino and it's evolutions, Zweilous and Hydreigon, were originally desinged to be cyborg tanks, but the idea was scrapped, then revived to look more like the mythical Yamata no Orochi.
Ken stated in the interview, "Deino, Zweilous, Hydreigon. At first, these incorporated an army tank motif, and the marks that look like a conveyor belt on the upper part of Zweilous's legs are the remnants of that. Initially, they didn't work as designs and were basically 'put to sleep', however, a three-stage powerful Dragon-type family was ordered and they were resurrected."
Contributed by Yoshiwaffle