Funny, I was messing around with max damage combos today as well. Dunno if this is more damage than the ones listed above because I'm not able to test those at the moment, but this does 11,819 damage, killing everyone but hakumen and tager. (12,000 and 13,000 hp).
opponent in corner, 3 rods, 100 meter
sj 8d, 2cd, 632146c, 632146c, 214a, 3c (hold), frog hits, 6c. 9d, 9d
I was trying hard to kill hakumen, but he still has like 180 health after the combo, and the last hit of the combo was already only doing 4hp per hit.