What are the special attributes of the four different elements that are used in the series?
Right now I'm discussing the special attributes of the celestrial elements which the cards fall under. This is seldom discussed, and if I find any citable information please add it here or to wikipedia. It's interesting that unlike in most fantasy series, the elemental cards (Chinese and Greek) both fall under jurisdiction of the Sun, Moon cards. As when Sakura's wood and wind cards (Chinese, and Greek/Chinese) are both deflected during final Judgement by Yue on the basis that they fall under his Jurisdiction as the Moon Guardian.
I don't know how to include this in the article, but so far these are the characters that I've discovered:
Sun-Kero, Spinel, Clow Reed (Sakura, 1st-2nd seasons?)
Moon-Yue, Touya, Ruby Moon, Clow Reed, Syaron
Stars-Sakura in the 3rd season
Darkness-Eriol (Clow Reed's reincarnation)
(There may still be others, for example, I'm not sure which element the sorceress from the 1st movie used. It does seem that more people draw from the moon element than any other element.)
As for their attributes, moon users seem to have more power during the full moon, but whether that is only at night and whether they are then more powerful than sun-users is a mystery to me.