I'd definitely reapproach the idea of Clash Man's exposed innards. Intended or not, it definitely looks like bricks. Perhaps following the contour of the head with some of the details and removing the dots. Honestly, for he and Quick Man though, I don't really buy the idea of the exposed inside being rusted and the outside not. I'm not saying that it couldn't happen that way, I'm just saying that it's such an unexpected approach, that the viewer will probably not read the red as rust. I think approaching them more like Metal Man, where the red is exclusively for worn paint might be better.
Have you updated any of the in-game boss sprites to match?