Beezletron- Based off Digimon charcter Beezlemon, this monster was a powerful and crafty opponent, able to even outthink and wound Sesshomaru. Beezletron had two forms, his base form which fought with a tomahawk and shotguns, used a motorcycle (though he was quick without it) , and had claws that could rip apart a demon orge with one slash. His super mode had a cannon which could hold back and repel Tessaiga's Wind Scar, and wings which allowed him to have an ariel advantage. He was destroyed with a combination of the Tessaiga's Bakuryūha (Backlash Wave) and Bakusaiga.
Gorz the Warrior- Based of the Yugioh card game monsters Gorz the Emissary of Darkness was a incredibly powerful enemy, but followed a code of honor ( much to Naraku's dismay). Had several ablities such energy waves, transportation, shapeshifting, and super strength, speed, agilty, and was an expert swordsmaster able to conquer Sesshomaru, Inuyasha, and Tenja at the same time. Still he wasn't nessecary evil, as he spared innocent lives as they had nothing to with his battle, eventually he learn there was more to fighting from Tenja and when he was captured he released him and sacrificed himself to allow him to escape. Althought he was destroyed Tenja found his sword and made a momument out of it in tribute to the warrior.
Duskfighter-Based on Digimon character Duskmon. Was a ruthless and bloodthristy warrior who would destroy an entire village just to anger Inuyasha. Had 2 swords which could crack Tessaiga and the eyes on his body had several ablities ( energy blasts, petrification, time freezing, ect). He was the shortest lived monster and was destroyed by Tenja's Sozo no Ken's Power Game.
Shadow Lightning- Based on Mega Man Character Rouge. Was a very quick and crafty creature with electrokinesis and teleportation. He was destroyed by Sesshomaru.
Dark InuyashaA dark image of Inuyasha with all of his powers, few of his weaknessses and a copy of Tessaiga. Was able to beat Inuyasha on a physical and mental level easliy, however had all the feelings of his template and Kagome and Tenja brought out his inner good and left to Japan to find his own purpose.