I'm fairly certain this trophy is for having your health go from a green bar, to a yellow and then to a red and complete the battle. If you're on a stage with a boss surrounded by enemies defeat the lackeys first and weaken the boss to near death. Most characters are similar to Ichigo in the respect that their triangle moves are a ranged move with some power. I used these to K.O the boss, however if you saved your ignition attack that will work just as well. If you die, you'll have to replay the entire stage over so be careful!