I think @Eruca made a thread like this with Homestuck so I thought doing this with Cardcaptor Sakura would be fun.
@Nights and Days - The Libra
The Libra is able to determine whether a person is lying or not, though its use is never demonstrated in the anime. It is one of the few cards not used in either the manga or anime, the others being The Wave and The Through.
The Libra Card shows a pan-scale, one side holding a sun and the other holding a moon. Libra's form is reminiscent of the astrological sign of Libra. The idea of the scale is also used as a symbol of justice and truth.
@Lady X - The Dream
The Dream is able to create all sorts of dreams, including prophetic ones for those with magical powers. Though it is not aggressive or malicious, dealing with it can be difficult, as it is relatively undetectable when one does not know it is nearby. Like with Return, Time can be used to disrupt it.
One of Dream's visible forms is a mysterious blue butterfly, that looks almost like the sky. Another form is a female humanoid with long, straight hair, dressed in a wide elaborate headdress that covers its eyes, perhaps indicating its status as a blind prophet, such as the Greek prophet Tiresias, and also indicating "sleep", since if one sleeps, the eyes are closed, and if one sleeps, he/she might have dreams.
@Azure Flame - The Firey
The Firey is a Clow Card with the the power to control or summon fire. This card is one of the four main elemental cards and was the third elemental captured by Sakura Kinomoto .
The Firey is one of the most powerful Clow Cards and is one of the two basic elemental cards that is directly connected to Cerberus (the other being the Earthy).
It has an aggressive yet somewhat arrogant nature as it seemed to have enjoyed toying with Sakura during its capture. It is no more powerful than the other elemental cards but is warned to be used with care. Cerberus warned Sakura that if she used it without care it would do as asked, but it could harm the user. Moreover, due to the trickster side of Firey, it has a tendency to backfire, scare, and/or even harm others while still technically doing as its master commands.
@AngelLight2012 - The Dash
The Dash (ダッシュ, Dasshu) is able to run at supernatural speeds for short distances. It can grant this ability to others as well.
Dash's visible form is a small blue, fox-like creature with long rabbit ears and a long slender tail. On its forehead is a small diamond shape mark.
Dash is shy and prone to give flight when given to confrontation. Once its trust has been earned however, it becomes very loyal.
@EJCC - The Shield
The Shield is Sakura's most-used defensive card, able to create a shell, force field or barrier around its target that is impenetrable to almost all physical and magical attacks, including the effects of the other Cards (i.e. Time, Shot). Unlike most of the other cards, Shield has a good personality.
In it's real form, it resembles a single 'Clow Wing' shield with a red jewel on both sides. In its card form the Shield is chained by several chains for some unknown reason, like the Sword. However it is one suggested theory that both are in chains due to them being the only cards to transform into actual weapons instead of calling upon an animated spirit (ex: The Arrow, which calls forth a young girl to shoot the arrow, instead of summoning an arrow itself).
@Wind Up Rex - The Sword
The Sword is able to cut through almost anything, including magical barriers. The card gains its strength from the heart of the person who wields it and gives the wielder the skills of a master swordsman. However, Sword can also overwhelm and take control of the person holding it, especially if he or she is non-magical. Sword is so powerful that it is even capable of penetrating through the Shield in Episode 11, thus enabling Sakura to capture Shield. The Sword can even slash through the time and space continuum warps created by the Loop in Episode 21, thus allowing Sakura to seal Loop.
More soon to come. Also I can try to do yours if asked (although there is a limited number of clow cards so they may overlap with other members).