I just said the duel trick.

Basically, you just let Zell do two moves repeatedly. I'm pretty sure I used Booya (O X) and Punch rush ( Up, down) and you keep repeating those two moves. People have done this so they've gotten over 400,000 damage on one duel. I can get usually an average of about 100,000 on one Duel, so it can easily beat Renzokuken. However, you can only do moves of about 2 buttons or less, because otherwise, it takes too long, and you don't get much in.