fight for +sth. 为(得到某物)。。。而奋斗/奋战
fight against+sb./sth. 与某人作战、对抗/和某种行为做斗争)
fight against nature 与自然界做斗争 fight against corruption 与腐败做斗争
fight with sb.=have a fight with sb.和某人打一架
是fight against
fight with 是与某人协同作战的意思
Don't fight against classmates.
Don't fight against your schoolmates.