Difficulty: Easy
While you'll probably get this in normal play, you can speed it up by taking away all Sheva's ammo and leaving her to fight the enemies, while you dodge and run.
When she gets grabbed you'll have to get close and follow the on screen prompt. Simply let her get grabbed again and again and repeat the process until you get your trophy.
Note: If she's getting low on health and dying then you can save her for progress towards another trophy. This can't be repeated as often though as she'll eventually die if you don't heal her.