Quote 4
"That's okay. […] You're a traitor to your own kind and not loyal to us." (8.98)
Ponyboy is speaking out of anger. He's offended that Cherry won't go to see Johnny on account of her loyalty to the memory of Bob. He seems mistrustful of anyone with mixed loyalties or inter-group relationships. Ultimately, Cherry's just trying to make sure nobody on either side gets hurt.
Quote 5
"An' you can shut your trap Johnny Cade, 'cause we all know you ain't wanted at home, either. And you can't blame them." (3.37)
Pony loves Johnny, but he has a temper, too. So he says just about the meanest thing possible. Johnny already believes that his parents abuse him because he's not a valuable person, and Pony knows that.
Quote 6
"A fair fight isn't rough […]. Blades are rough. So are chains and heaters and pool sticks and rumbles. Skin fighting isn't rough. It blows off steam better than anything. (2.91)
Basically, Pony seems to be arguing that fair fighting isn't violence but sport, an activity that's beneficial to energetic boys. What do you think? How is "rumbling" similar to or different from sports like football or hockey?