Tsukaimon is Vincent's partner in Digimon Demondestined. He is one of the six Rookie-Level Digimon freed by Beelzemon from the The Seven Great Demon Lords. Him and Impmon do not get along unlike their partners who are brothers and do everything together.
Tsukaimon is a Mammal Digimon whose name and design are derived from "Messenger/Familiar" (使い Tsukai?). It is characterized by its big ears. Although it is considered a subspecies of Patamon, it has quite the opposite personality as Patamon, so it loves brawling. Usually, it acts as a familiar for Devimon and others like him.
While the other digimon, Ronan, and Peter whent to free Sean, Eric, Diana and Rachael Tsukaimon heard Vincent's cry for help and went off to rescue him. On the way there Daemon gave him the Wrathful Data Link Digivice. Tsukaimon arrives in time to give Vincent his Digivice and scare off ShadowLeomon. Tsukaimon is the first of the digimon partners to digivolve to his champion form.
The name "Tsukaimon" refers to only the Rookie form of this Digimon. Throughout the series, Tsukaimon gains the ability to digivolve into a number of more powerful forms (each with a different name). However, the Rookie form remains as the most common and preferred form, due to the amount of energy required to stay in a higher form.
Devimon is Tsukaimon's champion form. He is the first of the digidestineds partners to digivolve to this form. In this form he is cold and uncaring but always tries to protect Vincent.
NeoDevimon is Tsukaimon's ultimate form. He is the first of the digidestineds partners to digivolve to the ultimate level. In this form Myotismon has a sick sense of humor and destroys his enemies without mercy.
MetalDevimon is Tsukaimon's mega level. He is the last of the digidestineds partners to digivolve to the mega level. In this form he barely talks and has a vicious and unforgiving nature.