3k + but honestly i dont know how the scores are being calculated lol

On S1 is this right now http://prntscr.com/cmlwot

Pretty obvious...

Remaining health is remaining health, end the battle with all your ninjas full health for max points.
Round Use Score is how long it took you. End the battle fast for max score.
Times died is obvious, don't lose any ninjas.
Total damage level score is how much damage you took, so interrupt every poison user and protect yourself with clones, don't just rely on healing.

It's easy for me to max out all three of the easy scores because I end the battle in record time with full health ninjas. But total damage is the trick, it's hard with my setup NOT to take damage. I just heal through it.