ORIGINAL: dostillevi
I've taken a few of the races you made and turned them into "spoilers" to make game play interesting. I pulled these races from your mod and added them to my own personal mod with 49 races...
The Zha'til are a capable but enigmatic machine race that inhabits ice worlds. They are ruthless and able to carry on war without penalty, but they have little reason to engage in war and won't usually be the aggressor in a conflict.
The Vandomar are an amphibious powerhouse, focusing on income and wealth. They tend to be friendly with other races. The close resemblance to the Asari suggests some shared heritage, but unfortunately many Vandomar do not see this in a positive light and so they are not fond of the Asari. The Asari have no such negative feelings towards the Vandomar.
The Ditakur give the Ursidians a purpose, as they are capable and also a bit xenophobic. Ursidians now have very strong affinity for each other and a slightly smaller affinity for the rodent races, for whom they should act as protectors.
The Rachni are an insect spoiler in that they dislike the more conniving insect races and are neutral towards or only slightly like the others. I've made them more intelligent than you had them, and the less xenophobic and more intelligent races will see that the rachni are more misunderstood than bad.
Lastly, the Endorumi are highly militaristic and xenophobic amphibian race. They like and are well liked by other amphibious races, and they respect power among other races. They detest humans and have low regard for other humanoids due to what they perceive as a meddling attitude.. Amphibians shouldn't have to stand next to humanoids as the chief galactic powers.
As you can probably imagine, I don't know much about what these races are supposed to be like in the ME universe!
Hey, what about Protheans?
BTW: Info on these races is here - http://masseffect.wikia.com/wiki/Background_Races