There is no "marsh" dragon in dragonvale but if you are referring to the moss dragon the best way to get it is earth and plant, although you also have a chance to breed the tree dragon.
You don't breed a Kairos Dragon in DragonVale. You have to get parts to complete it.
you breed a ice dragon with a mine dragon
You have to breed a plant and a fire dragon.
As of July 2012, there has not been a star dragon in DragonVale.
You have to breed a sun and moon dragon together
You have to breed a metal and a water dragon together.
You have to breed a plasma dragon with a salamander dragon.
Breed the earth dragon with the fire dragon.
To get a Smoke Dragon, breed a fire and air dragon together.
Earth Dragon and Cold Dragon
Another dragon
Breed a Crystal dragon with a Cactus dragon.