Metroid: Federation at War for Forces of Corruption allows players to chose to play as either the Galactic Federation with Bounty Hunter Samus Aran and Commander Adam Malkovich or play as the Space Pirates with the Evil Phazon being Dark Samus and Geoform 187, Meta-Ridley.
Mother Brain controls the space pirates on Zebes and is a main antagonist of Samus Aran.
just something to compare the last image to.
my favorite boss, other than ridley :)
This image from Metroid: Zero Mission was also used to create the helper icon on the command bar for the Pirates, as of Metroid Prime Conquest version 2. True story.
Metroid.retropixel.net Have you tried this site. Might get some inspiration for new models etc.