Hmm...ok, so let's see where we are....
Outsiders and Starseeds: not a clue....
Propulsion: various fusion drives, and some gravity polarizing drives (Kzin get them early). Kzin and maybe others get multiple propulsion types per hull. Unlucky in wars but incredible warriors.
Hulls(Ships): 4 GP hull standards, some experimental hulls and some unique hulls per species....And I guess you could have some interesting hull mods, ie opacity to certain frequency lasers or something
Weapons: Com Lasers, fusion cannon based on drives. since com lasers also represent strategic advantages, maybe an attack bonus based on comlasers?
Fighters and drones: I don't think there is a carrier in this universe, but I can easily see them as planetary defense...well, maybe....
Interesting structures: A ringworld could be very difficult to make...but I'm willing to bet that the Massive Space Dock in the Ultimate Mod is a Builder/Pak artifact.
Puppeteers: we assume the puppeteers have left on the great migration away from the core explosion. The Puppeteers become an incredibly advanced, defensive neutral. Attack them and die by the numbers:
Humans: lucky (ala teela brown and the pop lottery), diplomatic (ala louis wu), cunning (ala beowulf shaeffer and gil the arm), any other thoughts?
Thrintun: very weak and technologically poor, but incredibly powerful intel attacks for tech theft and unit insurrection (might need a planet insurrection). Is it possible to have unit insurrections during combat? Non GP hulls.
Tnuctipun: very weak but technologically very advanced, only species that can develop helmet technology that creates humongous intel defense against Thrint. Non GP hulls.
Kdatlyno: neutral warrior empire, with special sonic capabilities technology tree. maybe they start off subjugated to the Kzin?
Pak: (heh) Incredible troops and combat advantages, high tech ability, no diplomacy at all, only expands after meeting another empire, very slow expansion. Does not use GP hulls, starts off with weaker fusion drives. prolly a unique technology tree with lots of gravity weapons. strong tendency to large fleets of smaller ships.
Bandersnatch: might be difficult.
Trinocs: All I remember is that they are incredibly xenophobic and racist.
anyway, these are just some thoughs
(Laffing, I expect I have a lot of gray matter out there right now thinking about this one )
:Jon