The most effective way of breeding a plasma dragon in DragonVille is Seaweed Dragon (level 10 on left) and Lightning Dragon (level 10 on right). This has about a 25% success rate.
The plasma dragon egg is yellow with turquoise horizontal wavy stripes. It takes 16 hours to breed, and 16 more hours to hatch. It becomes available at player level 14. It gives 75,000 experience points upon hatching. You may also purchase a plasma dragon from the market for 40 gems.
Other breeding combinations that work are:
The most effective method of breeding a jet dragon is using an ash dragon and frostfire dragon. This has a 15% success rate. The egg is black with etched black designs, and takes 30 hours to hatch.
Lightning and fog. Keep trying if it doesn't work.
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
Another dragon