General Intelligence:
* Sharpness
* Astuteness
* Sagacity
* Acumen
* Brightness
* Wit
* Ingenuity
* Brainpower
* Genius
* Cunning (can have negative connotations)
Cleverness:
* Resourcefulness
* Shrewdness
* Quick-wittedness
* Ingeniousness
* Deftness
* Savvy
* Wits
Specific Skills:
* Analytical
* Logical
* Strategic
* Creative
* Intuitive
* Innovative
* Learned
* Erudite
* Scholarly
Informal:
* Smart
* Bright
* Sharp
* Quick
The best word to use will depend on the context and the specific type of intelligence you want to emphasize.