Huck decides not to tell anybody of Jim's escape because if Jim stayed back, he would have been sold. Huck and Jim are both alienated from the society in a number of ways. Their fates are linked right from the first part of the novel. Freed from the hypocrisy of the society they create a heaven of their own.
The past participles battered and bruised are both intended to modify the noun team, the head of the noun phrase the football team which serves as the subject of the main clause.
