MK can be assumed to move... If you remove his pauldrons and boots. MK's body is too small to function properly with added weight. Also, because he is the same species as Kirby, he cannot have hands via those gloves.
It would mean that he has hands too large for his body proportionally, and just swinging them can set him off balance. His arms, like Kirby's, are stubby, and thus, while he could possibly have the muscle to move, he cannot have the muscle to swing Galaxia with enough force to wound DDD, or even lift it. Heck, Meta Knight having his armor on makes him nigh short of being completely immobile.
I said this back in the Kirby and Jigglypuff MU, while they can move, they cannot do anything to one another. The same goes for Meta-Knight. He cannot have hands due to being the same species as Kirby, whom has no hands, and thusly would also have trouble gripping anything, so him being able to use Galaxia to any effect is not possible.
DDD can't do much to him either. He has the same problem with his legs that Kirby has with his arms, except that he could maybe waddle around. His arms also do not indicate muscle tone (this of course is only assumed because we can't see what his arms look like underneath, even if his arms was particularly muscular, that coat would make them seem formless).
I think neither combatant wins this one. =\