Here were go again. These threads always go this way. That's why I made this pasta.
Races that would lose horribly to the Culture:
- Anybody from Star Trek, even if they all ganged up on the Culture. Some races would last longer than others (The Borg). The exception is the ascended beings (Q, Metrons, Organians, etc.) since the Culture universe ascended beings just don't care.
- Likewise the Stargate races (though the Culture would probably get along great with the Asgard and Nox)
- The Empire (Star Wars)
- The Imperium of Man, unless Chaos ate the Minds, which it probably couldn't.
Races that would be a challenge to the Culture or would at least take a long while to overpower:
- Civilization at the Children of the Lens time period (an entire galaxy of worlds churning out ships, intergalactic travel in reasonable time, Sunbeams, Negaspheres, etc)
- The races from Total Annihilation (increadibly fast production)
- Fourth Imperium at the height of its power (Heirs of Empire series) (Fleets of moon-sized warships)
- The Daleks (apparently they are more formidable than they appear)
- The major races of the Schlock Mercenary setting (Or Petey, at least)
- The races from Perry Rhodan
Races that would school the Culture:
- The Time Lords, via time travel, black hole weapons, etc.
- The Xeelee
- The Photino Birds
- The Downstreamers, Oh God, the Downstreamers could school everyone else here put together.
The Culture, The Xeelee, The Photino Birds, and the Downstreamers would all crush the Imperium, as would the Time Lords.
TA, Civilization at the Children Of The Lens time period, the Fourth Imperium, The Daleks, the major races of Perry Rhodan, and the Fleetmind and Panuri from Shlock Mercenary would all be big trouble for the Imperium but might be defeatable.