Goblins: I'd pull from the smaller kobolds.(gougers, flingers etc)
Fimirs: Iron scales would work just fine
Chaos Warriors: Dread Knights for days
Gargoyle: Roxor is my first instinctive choice because of the rock form. Due to base size I'd prob defer to Von Drakk
As for mummy, I'd run the boneheads, whilst running rattle bones as skeletons.