I noticed that Minazuki's slashes have more hitstop in comparison to Sho, so this might be the reason why he can SB Metsuga> 2A.
If you're talking about the Fatal Counter loops, then you should try this combo:
FC 2C> dash 2AB> 236A~B (JC)> delay [j.C> 5C 2AC]x 2 j.C> 5B(1)> 2B> 2AB> 236B~ delay B~C~214A~A
Work on virtually everyone, midscreen, corner, does good damage and is pretty reliable.