If your Str stat is at 255, and you use Meltdown, and it's not doing 9,999, then it's not going to do 9,999. The physical damage done to an enemy also depends on that enemies Vit stat, but then again, that should be irrelevant given the Vit O status caused by Meltdown. For the record, my individual Renzokuken strikes usually dish out damage in the low 9,000's on a Vit O'ed enemy.