An inanimate suit of armor from Dino Earth that turns whoever wears it insane, causing them to kill anyone in sight. Whoever defeats its wearer will become the new wearer. This suit had multiple owners over the course of the series.
A cyborg warrior working for Mesogog. Was previously a human scientist named Terrence "Smithy" Smith. A lab accident left him badly injured, but was rebuilt into a cyborg by Mesogog.
Held no particular rivalry towards anyone, because it was an inanimate object. Its primary wearer, Jannu, did have a rivalry with Asuka.
Was an arch rival to Tommy Oliver, because he felt the lab accident was his fault.
Was worn by Asuka, then Geildon, then Jannu, then Asuka once again before it was destroyed when two people defeated it resulting in it dissolving when it bound to Mikoto's body.
Since Zeltrax was a carrier of the armor, nobody used it.