Grubb

Grubb (translated as "Glab" in a fan scanlation of Zatch Bell! The Card Battle) is Koral Q's partner. They are a team encountered by Zatch and Kiyo.

Grubb uses his incredibly high IQ to do research about each mamodo, and then get its weak points or see how strong it is. Grubb is an extremely smart teenager who thinks that everyone else is "trash" because he's the smartest one, but after Koral Q's loss he start making friends.

(Source: Zatch Bell! Wiki)