“What evidence points towards Martin being the aggressor?”
The question is, “what evidence points toward Zimmerman being the aggressor?” State has to prove that beyond a reasonable doubt.
So far there seems zero evidence of who - once they met up - started the violence.
And it may be a moot point - apparently if the law is interpreted as written - a person can start a fight, determine that their life is in danger if the fight continues, and then draw a gun and use deadly force to stop the fight.