Your birds seem to have pretty good type, but as already stated, their mottling needs to be worked on.
As they say, size and type comes from the dam, and color comes from the sire, but never breed a "steller to a steller." Aka, don't breed a bird with excessive white in it's plumage to another bird with too much white in its plumage, or a bird with an extremely short back to a bird with an extremely short back. You would get excessively white birds with impairingly short backs. For that first hen you have, and the younger blue mottled pullet, I'd get a rooster that doesn't have a whole lot of mottling on him.
So, for example, separate off your black mottled roo with your mostly blue colored hens, they should produce chicks that will be somewhere more close to what people are looking for in mottled cochins.
So, I hope that helps. I raise and show mottled cochins of my own, and sometimes show people are just plain buttheads. Don't listen to them, just plan a sneaky and painful revenge, ahah.