For me the zombie king was the hardest to take down.
I tried using sparkle flower, demented bulbs and dam'bl'don bell and the last one worked sometimes however the sparkle flower and demented bulb did not for me.
I made sure my game characters were protected from as much of the red, blue, white and black attacks.
Of course Jeanne is necessary for mega boost and omega red if you have it and just make sure to stay alive and cure all negative status effects quickly.
That was my strategy with this zombie king.
