I mean it would look something like this:
1. Humans would be the most "GC2" like of the races. Strong diplomacy, average at most other things.
2. Altarians would have certain mystical abilities. That and they would be somewhat like the humans, but with their own ideals.
3. The Drengin would be unique in that their economy operated heavily on slaves (maybe from the other worlds too, ex: Torians slaves). Strong weapons and troops, maybe strong (slave based) economy. Weak at diplomacy, culture, and maybe population growth?
4. The Yor would be unique. They're robots, so expanding on the GC2 theme would be nice. Special robotics too would be nice. I'd make them immune to being culture flipped, and to revolts, but say in return, they cannot culture flip or produce other culture.
5. The Iconians may bear some resemblance to Yor technology (common origin), but they are biological so they'd be kind of a hybrid in a sense. Plus they're "good". They'd be an interesting amalgam of some Yor tech, sans the culture immune part.
6. Thalan ought to be totally different from everyone, since they're from a different dimension. They should have some very powerful, but very unique abilities.
7. The Krynn should be a hybrid of everyone, with their own traits too (maybe not Yor though). They'd be strong on culture, but the middle of the road type of race.