[quote=@FacePunch]
The slugs sound more interesting, in my opinion; that would also give more reason for the Matriarchy for creating combat AIs such as Y00-17. Although the idea of fighting an entire alien race like Sonic humors me.
[/quote]

The slugs developed a program that shut down a lot of the AI so only Y00 got out of the war just in time. The slugs aren't fat or slow but instead look majestic. 

They don't look like sonic, being more like realistic humanoid hedgehogs. They could be a rival but not the main one. The slugs are a major threat. Oh yeah, and the GAN empire has a super powerful cactus race that was a major threat long ago when the two factions were fighting, but luckily they are currently at peace.