I was in a game with Assaj and Latts crew. At one point, I had a structural damage crit to reduce my evade dice AND I got tractor beamed. Combat phase starts, I stress the nearest attacker with Assaj, but I'm throwing no green dice. My friend said I couldn't use latts crew, as it specifically says "When defending, you may remove 1 stress token from the attacker to add 1 evade result to your roll." Because I was rolling nothing, no latts. Was he correct?

No.

You still go through the dice modification steps as normal, and you can add results to a 'roll' of 0 dice - otherwise the Ghost having the Evade action wouldn't really help...

If the game intended you to have to roll at least one die for a thing to work, it would say so - compare the wording of C-3PO crew.

Second to what spaceinvader said.

Rolling zero dice and rolling all blanks is functionally the same thing in this case and obviously rolling a double blank doesn't turn off Latts.

Just gonna leave this here....