Calumon acts differently in different languages. In the English and Brazilian version, Calumon's immature antics and over-expressed emotions leave little doubt about the fact that his role is not of a fighter. However he is still shown to be kind and brave. The German and Japenese versions show that although he is not a fighter, he is very brave, kind, and mature. He is also very good at making others feel better as best shown near the end of the series. In Digimon Tamers, Calumon is the only Digimon on the protagonist's side who had no official tamer, although he does seem to have a special bond with Jeri as he was able to sense her presence when she was trapped inside of the Kernel Sphere. He then led Beelzemon in a rescue mission to save her, and helped her immensely when he finally snapped her out of her depression and protected her from the Chaos with a forcefield during the final battle. He may have become her new partner after the events of the D-Reaper Saga of Digimon Tamers. In the beginning of the series, Calumon thinks of the Real World as a game and the humans as other digimon. His ears, usually short, can be expanded, usually when Calumon is happy or excited, to the size shown in the picture to allow him to "fly". His forehead bears the symbol which is the polar opposite of the Digi-Hazard. It is called the "Zero Unit." It is from the Zero Unit symbol that Calumon releases his power to catalyze Digivolution. In the Arabic dub, Calumon does not have the symbol on his forehead.
Calumon is a unique digimon who does not Digivolve, and cannot be Digi-Modified. However, he seemed to use a "Crystal Matrix" when Growlmon first became WarGrowlmon, suggesting that Calumon powers Digivolutions. Another instance of this ability is when he was very excited in the Digital World. This created a trail of shining light that digivolved some Woodmon into Cherrymon. Calumon is eventually told that he is the "Catalyst", the light of digivolution, and he releases his power to digivolve every Digimon in the Digital World to Mega in order to fight the D-Reaper.
In the series Digimon Tamers, the Digimon Sovereigns reveal that Calumon originated as the element of Digivolution—the realized version of the "Digi-Entelechies" (Digi-Entelechia). In order to hide this power from the evil D-Reaper, they turned the power into the form of a Digimon. In the end of the series, the Sovereigns restore this power to the Digital World, but allow Calumon to continue to live as an ordinary Digimon. Calumon plays a pivotal role in the last few episodes of the series detecting Jeri's presence and launching a rescue mission for her with Impmon for back-up. Thanks to Beelzemon Blast Mode (Impmon digivolved to fight off some D-Reaper Agents) he gets into the Kernel Sphere where Jeri is and does his best to snap her out of her depression. He ultimately succeeds in getting her to fight back against the D-Reaper and to realize that there is something worth living for. After she cracks the Kernel Sphere with her D-Ark, freeing them but letting the Chaos Mass in, he somehow protects them with a forcefield and gets them outside the Sphere. The two are eventually rescued by Takato with help from Guilmon. He is forced to return to the Digital World with the other Digimon at the end and says his goodbyes to a grateful Jeri.
In the Japanese and Brazilian versions, Calumon had a habit of saying "culu". This was removed from the American dub, but readded in the Southeast-Asian version of the American dub, using "calu".
Calumon is voiced by Tomoko Kaneda in the Japanese version and Brianne Siddall in the American dub.
Calumon appears in Battle of Adventurers and Runaway Locomon, but does not play a major role in either of them. He's there for the final battle in Battle of Adventurers and somewhat saves the day by causing Growlmon, Gargomon and Kyubimon to digivolve to WarGrowlmon, Rapidmon and Taomon because he got scared of Gulfmon which allowed them to finally destroy him with their Trinity Burst attack. In Runaway Locomon he serves food at Rika's party flying around carrying a tiny dish with food to the others.