First make sure the game is on Novice and rounds are set to 1.
I find it best to use lots of combos and just stay on top of him. Also keep switching up styles and moves.
With all the above you should be on your way to beating up on the Dragon King.

Heres one way that has worked with me for all the chars. Bust a post thing, then while he's down unleash a weapon combo on him (one thats quick and easy to pull off, but DOES good damage.) Followed by another if your quick enough. Then repeat untill he's dead, Don't get close to him cause his grab move is SO damn annoying! And watch out for the fire as far as I know you can't dodge it in anyway and it does a large amount of damage.

Thanks for your help guys. I will try it later :)