Dorumon

Dorumon is a Beast Digimon whose name is derived from " D IGITAL OR U NKNOWN MON STER". Because of the old-style interface on its forehead, it is thought that Dorumon is an experimental prototype Digimon from before Digimon were discovered. Initially this Digimon's battle-personality had manifested too strongly, but it seems that it was eventually tamed by someone it had bitten. In an experiment, it was discovered that hidden deep within its DigiCore is the data of a legendary dragon, and it is thought that this gives it the ability to grow into a mighty Digimon. It naturally carries the X-Antibody, causing it to be ostracized by its peers, but its existence will turn out to affect the fate of the Digital World itself.

Digimon Chronicle
Dorumon is Kouta Doumoto's partner. He soon digivolves into Reptiledramon in 1.5, but is a Dorugamon in 2.0.

Digimon World 4
Dorumon is a Bash specialist, and is one of the four starting Digimon.

Digimon World Data Squad
http://digimon.wikia.com/wiki/User:Maitkarro/DW_Data_Squad#Dorumon

Digimon World DS
Dorumon digivolves from Dorimon, and can digivolve further into Dorugamon with high level and high Beast EXP. Dorumon also prevents you from entering the Back Equipment and Back Item Shops if you are not a Silver Tamer.

Digimon World Dawn and Dusk
Dorumon digivolves from Dorimon and can further digivolve into Dorugamon with 800 beast exp, attack 125, level 24 or Drimogemon with attack 90, level 19, and minimum aptitude of 25.

Attacks
 * Metal Cannon: Shoots metallic projectiles from his mouth.
 * Dash Metal: Charges opponents with metal-armored head.
 * Hyper Dash Metal: Launches metal that freezes the enemy.