Zeromaru

Zeromaru shares many of the personality traits belonging to his human partner Taichi—he is very strong willed, but somewhat fool-hardy, and hates to be underestimated. He acknowledges the fact that he can't do everything on his own, but is determined to prove his strength nonetheless. Throughout the V-Tamer 01 series, he fights against many powerful Digimon, and often wins only because of Taichi's tactics.

(Source: Digimon Wikia)