Mother Brain had a special GIR for Ridley after that last screw-up on Tallon IV.
Ridley: Finally! A space pirate under my command!
Mother Brain: Um, we have a top secret model for you, Lee.
[Junk parts, nuts, bolts, and an old NES cartridge go into Meta-Ridley, herein referred to as MER (Metallic Ridley, the E stands for an unknown purpose).]