I could see an odd Marble King. In fact, I found it in my MK drawer when I was rummaging though them this morning. So that must be what I originally thought too. lol
The pattern looks right but something seems a little off to me . . .
A weird 6 ribbon Rainbo? A Wolverine with an unusual ribbon pattern? A weird Marble King?
I'm not feeling Champion and I think it could be one of a few different companies'. Sometimes these single color swirls can be tough to ID with any real certainty.