Ikkakumon

Ikkakumon is a Sea Animal Digimon. His name is derived from the Japanese word "ikkaku", which means single-horn. He is a large, furry, walrus-like creature with a horn on his head and paws on each foot. He is a very able swimmer. His fur can withstand the coldest of lands. When he's not moving, his giant body is like a white gun platform.

Digimon Tamers
Ikkakumon is one of the shadowed Digimon who wanted Rika to tame him as a Partner.

Digimon Data Squad
Ten years before the events of the series, a Gomamon emerged from the water and Digivolved into Ikkakumon where it attacked Spencer Damon's group (it had enraged after Akihiro Kurata shot at one of the Digimon).

Digimon World 2
Ikkakumon digivolves from Gomamon and Penguinmon, and can digivolve to Whamon or Zudomon.

Digimon World 3
Ikkakumon is only available as a Blue Champion Card with 13/13.

Digimon Digital Card Battle
Ikkakumon is a Champion level Water deck card. He appers in session two in Igloo City.

Digimon World DS
Ikkakumon digivolves from Gomamon, and can digivolve to Zudomon. Ikkakumon also appears in Drain Tunnel.

Digimon World Dawn/Dusk
Ikkakumon digivolves from Gomamon (which digivolves from Poyomon). The easiest way to obtain it is to degenerate (de-digivolve) a Zudomon. Zudomon appears in the Access Glacier area after completing, "The Combat Game" - Machine Quest.

Attacks 
 * Harpoon Torpedo (Harpoon Vulcan): Shoots out several horned-shaped rockets from his horn, each one opening and revealing a small torpedo inside.
 * Icicle Coat: Thin icicles sprout from Ikkakumon's body, freezing enemies around him.
 * Belly Flop: Jumps in the air and falls on enemies with his belly.
 * Horn Attack: Attacks and strikes with his horn.
 * Heat Top: His horn becomes very hot and he strikes opponents with it.