how do the boys describe greasers

I am going to assume that when you say boys, you are talking about the Greasers themselves? Ponyboy describes the Greasers as loyal, that their code for behavior requires them to stick up for each other at all times, especially to the authorities and to their rivals.

They define themselves by toughness and invincibility; they'll take part in rivalry and violence, but NOT ever will they hurt children. The greasers can't afford thing, but they will steal things. They distinguish themselves by the way they wear their hair, the "grease," and by allowing it to grow out. This is their mark as a group. Even the Socs know this, which is proven by the fact that they threaten to cut Ponyboy's hair; for them to cut his hair would be to take away his identity.