Not the Blue Blur
would be my choice. The rest of the title suggestions have been clever attempts to avoid being so blatant about that, but ultimately, that's the joke and I don't think the joke gains anything by being obfuscated. Some of the suggestions (orange in sharp contrast, most notably) are very clever ways of saying the same thing, but to me the more clever suggestions really take away from the fact that Metal Sonic is Not the Blue Blur
.