there are a lot of ways, but the most effective way is blazing (air and fire) and water
Go to the breeding cave or epic breeding island and breed the earth and air dragons. Also there is a dragonvale breeding guide app
The most effective method of breeding a coral dragon is using a water dragon and fire dragon. This has a 30% success rate. The egg is blue with red flames, and takes 11.5 hours to hatch.
Today!!
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.
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.
Earth Dragon and Cold Dragon