I had some trouble until I figured out Behemoth's Desperation Move gives 35,000 points upon hit.
To select Behemoth, put cursor on Syuten-Dozi in character select and press A,Y,A,Y,A,A,Y,(X or B). The desperation move is quarter circle back, quarter circle forward, B+Y. This can only be done when your energy is very low or you have three lightning runes charged up.
Here's video showing you this in action: