I actually did all the 'A' grade players, and even B's, with Mitsurugi.
His Up+RB move, where he jumps into the air and lands a powerful vertical attack is fantastic.
This works wonders on all characters, especially those that attack a lot/constantly, such as Leixa, or Astaroth. Astaroth does his swinging, or head butting moves a lot so this catches him off guard a lot. Just don't go near the edge, just in case he or anyone do catch you.
Even if/when the computer is blocking and you hit, it does a lot of damage to their shield, and will soon give you the free shot, from when you break their blocking.
From time to time, throw in the odd other moves, nothing difficult, just a simple DOWN+B followed by Y. This will do a low attack followed with a nice vertical, that does take a decent amount of damage, and it does catch them most times, or do BACK+B, followed by Y. This doesn't hit as much from what i have seen, but its good to mix up.