How do you kill the grand master of all things bad in one hit

I recommend that you choose to be a Lucario and use Focus punch when he is a tile away, then he should move forward, then it will hit for about 300-700 damage, depending on your level.
But if he is right in front of you then you should consider linking 3 moves: Endure, Force palm and bite, OR Force palm, bite and Brickbreak.(The TM)