This trophy is a little harder than the SS rank one, and as they don't stack you'll need to try to get this trophy on it's own.
I found the easiest way is to find a strategy that allows you to get the SS rank and keep using it, over time the enemies will get hard enough that the SS rank is not obtainable, and as such you'll unlock the S rank
As such here's my SS Rank strategy.
"The easiest way to beat this is to find a really cheap move.
First set the difficulty to very easy (so the opponent really doesn't block).
Then set the timer to the highest setting so you get the best time bonus.
I found Kyo Kusanagi to have a really easy move (he's the first character in the list so he's easy to find). If you do a half circle from front to back (going down) you'll get a charge move that grabs the opponent and then damages him. If you continue to do this in the first match you should be able to wipe out all three enemies with out a challenge. You can even start the run before the enemy gets up to almost guarantee a hit. You do not need perfects (I didn't get them) but they will help your score. You'll only need a high score."
I found that using this strategy on stage 2 of the very easy playthrough somehow got me only an S rank, and this trophy.