TetsuGold, the leader, is Tony Stark. Bethany Cabe is TetsuViolet, Pepper Potts is TetsuPink, Happy Hogan is TetsuGreen, and James Rhodes it TetsuBlue. The mysterious TetsuBlack shows up about a third of the way into the series, and the identity of the operator is a mystery...eventually it's revealed to be Ezekiel Stane (the "mundane" enemy of the series so far, kinda like a Bulk&Skull character, but not comic relief), who hacked the Morphing Grid to get the plans for the TetsuRanger suits, and is determined to avenge his father's death at Tony's hands by simply being a better hero than Tony's entire team put together (taking "living well is the best revenge" to an extreme conclusion). When the truth comes out, Tony and Zeke come to blows, but eventually realize that the world is better off with them on the same side...if different angles.
Obviously, the main non-mundane villain of the series would be the Mandarin, and he'd have control over Fin Fang Foom, Ultimo and maybe some other imported monsters not normally associated with him in the comics.
Step one in each non-TetsuBlack case was to brush on a thin layer of metallic red paint. Once that was dry, pick the Ranger Color and paint the yellow parts in it (TetsuGold uses "antique gold" non-metallic paint). The unibeam/arc reactor was painted a lighter shade of that color, with a lighter-still shade blended into the center. That lightest shade was also used for the eyeslit. When I dyed a figure black, I found a differential absorption rate. The head, upper arms and upper legs went solid black very nicely. The other parts turned a sort of very dark red with a faint metallic cast to it. It looked kinda nice, but I eventually decided it didn't fit what I was looking for. I painted the faceplate, biceps and thigh armor with chrome, and used silver paint for the arc reactor. I took a fine black pen to fill in the eyeslit.