I see Vorlons and Shadows as essentially opposites. Both highly advanced with very different views on how the universe should progress.

The Vorlons are all for order, discipline and obedience. I see them as secretive, insular, unprepared to interfere or share knowledge or provide assistance until they deem that particular race worthy. They see themselves as the true guardians of the galaxy even if it means using force to keep various races and factions in line.

The Shadows on the other hand represent chaos, and progression of the species through conflict and survival of the fittest and do what they can to stir the pot and promote this. As with the Vorlons they are secretive but they are more active in achieving their goals. What they want is purification and advancement of the races via conflict.

I hope this will help kickstart the discussion.

With regard to the main races excluding the first ones I've commented below. These comments may or may not fit in with the traits etc that the game has set out for us.

Centauri: based on Roman Empire. Mercantile, perfidious, given over to intrigue and continuous plots to advance their power base and influence. This can bring them into conflict especially with the Narns. They are advanced in the art of siege warfare including the use of banned mass drivers to decimate planets.

Humans: are essentially as the vanilla game portrays them, except, as with the Centauri, they are not above employing intrigue to further their goals. Their ships are generally inferior to other races relying instead on intrigue and diplomacy to create alliances and trade agreements.

Narns: militaristic, vengeful, who seek to punish the Centauri for perceived crimes made against them. Narns physically imposing with more powerful ground forces than most. Their ships boast some lethal fire power and under the right conditions and given the opportunity are capable of destroying with their capital ships a shadow vessel.

Minbari: are spiritually minded, peaceful unless provoked at which point they can be downright ruthless. Humans acting the proud, bumbling diplomats naturally found this out to their detriment.

How one translates these traits into the game's mechanics of course is open to interpretation.

I have to agree with Vorlon-shadow opposites.
xenofile - xenofobe can make one choice. Shadows were very open to contact and vorlons are very distanced from everyone.
I picked militaristic for shadows due to their desire for conflict.
And materialistic along with NNA government should have reflected "guardians of the galaxy" persona.

Do you think spiritual oligarchy is too good for narns? (as well as spiritual trait)

What about engine techs? Most races primarily use a Jumpgate (Wormhole) in the show but most of the larget ships have the jumpgate tech built in, (warp). The vorlons and sha'dow can easily be considered warp tech... but do we limit all of the minor races to the same tech? Which engine tech best suits each nation?

Fanatic Pacifist seems wrong for Minbari. Not only did they go to war with humans, they also actively participated in the Shadow War and built large numbers of White Stars.

I might actually even give them Militarist. Spiritualist, Militarist, and not sure of the third pick.