[Nexus]

Так?

var colors=[[255,0,0],[0,255,0]],
	shades=[];

colors.forEach(function(color,index){
	shades[index]=[];
	let counter=255;
	while(counter){
		shades[index][counter--]=color.map(function(val){
			return !val?val:val-counter;
		});
	};
});

console.log(shades);