RareRaremon is an Undead Digimon. It is the Ultimate of Raremon who has survived the advanced decay of its body through further mechanization and has taken on a bizarre appearance. Its body repeatedly breaks down and takes form, and eyes and mouths have emerged which are rotting away. The foul stench it gives off from its entire body has increased so much that even Megas have difficulty approaching it. Because it consumes energy to maintain its body, it makes up for that energy by dissolving the enemy with its "Digestion" (Digest).
- Digestion (Digest): Dissolves the enemy after it swallows them whole via the mouth on its head.
- Decayson: Toxic gas spewed out of its many mouths. Enemies that inhale it die instantly.
It resembles a blob of decaying green flesh with cables embedded in it. It has multiple protrusions with mouths, numerous eyes and its head is covered in metal plating around a massive mouth. Like Raremon, its design is based on the fictional Hedorah.
- RareRaremon (レアレアモン)
Official romanization given by the Digimon Reference Book and used in the franchise.
A Raremon that Garbagemon has been seeking revenge against digivolves into RareRaremon after being hit by dark lightning and he proves to be more than a match for MegaKabuterimon and MetalGreymon. Realizing that his body is filled with oil from how much of it that Raremon ate, Izzy Izumi comes up with a plan and has Tai Kamiya throw packets of waste oil hardener into RareRaremon's body before having MegaKabuterimon spin him fast. On Izzy's signal, MetalGreymon heats RareRaremon up with his Giga Storm before Izzy attaches Garbagemon's Absolute Zero Bazooka to MetalGreymon Alterous Mode's blaster. At Izzy's command, MetalGreymon charges the bazooka with his power before Izzy fires it at RareRaremon. Combined, the plan hardens RareRaremon solid, leaving him trapped forever immobile in a junkyard.