Infermon

Infermon is an Ultimate Level Unidentified Digimon. Its name is derived from the word infernal.

Evolution

 * Fresh (Baby I) - Kuramon
 * In-Training (Baby II) - Tsumemon
 * Rookie (Child) - Keramon
 * Champion (Adult) - Chrysalimon
 * Ultimate (Perfect) - Infermon
 * Mega (Ultimate) - Diaboromon, Armageddemon

Attacks

 * Spider Shooter (Hell's Grenade): Opens his mouth and a cannon comes out and fires.
 * Network Grenade (Coccoon Attack): He withdraws into his shell and thrusts himself at his enemies.

Digimon Adventure: Our War Game!

 * Voiced by Paul St. Peter

Keramon digivolved straight to Infermon, thus bypassing the Champion level. In this form, Greymon and Kabuterimon had a hard time fighting him. To defeat the powerful Digimon, they also planned to digivolve on their Ultimate Level but while there were digivolving, Infermon attacked them, resulting in their defeat. Infermon then escaped and hacked himself in the US military network, from where he launched a nuclear missile on the DigiDestined. Agumon and Gabumon attacked him in their Warp Digivolved forms, WarGreymon and MetalGarurumon. However, as the strides were against him, he evolved into Diaboromon, nearly killing both Patamon and Tentomon. This greatly enraged Tai and Matt, and they began to pummel him, that is, until Taichi's computer froze, causing Wargreymon to do the same. Without the help of Wargreymon, MetalGarurumon was easily defeated by Diaboromon.

Digimon Tamers

 * Voiced by Richard Cansino

While Beelzemon was testing his new powers on a bunch of Chrysalimon, Calumon's power Digivolved the remaining Chrysalimon into an Infermon. However not even he could bring down Beelzemon, who destroyed him and absorbed his data.

Digimon World 4
Infermon is seen everywhere in Machine Pit.

Digimon World DS
Infermon evolves from Chrysalimon, and can evolve further into Diaboromon or Beelzemon depending on its stats (and, for Beelzemon, if you've already owned one before).