MISSABLE!
Note: This doesn't have to be done in one battle, it can be done over multiple battles.
Ginger kids (a.k.a. hallway monitors) are only found the first time you are in the school, when you have to rescue Craig from detention. The quest "Detention Sentence" will take you here. Now, this trophy is kinda luck-based as you won't always get bitten by them, as they use random attacks on you each time. When you are in a fight with them, sometimes they will use the move "Ginger Bite" on you. This is the one you need to not block. There is only 3 or 4 battles with the hallway monitors, so you need to drag each battle out as long as you can. To do this, just don't press or when attacking. This will either not cause any damage to them at all, or very little damage. Once you get the "Ginger Bite" attack used on you 3 times, the trophy will unlock.