Delaware County prosecutors also dropped all charges against the teen who taped the attack in which the 13-year-old victim was dragged through the snow, stuffed in a tree and hung by his jacket from a 7-foot-high fence post.
The victim agreed with prosecutors' offer to drop felony aggravated assault and kidnapping charges in return for admissions to misdemeanors. The teens will remain in custody until a juvenile detention hearing scheduled for February 22.
The final suspect denies any wrongdoing. His trial is set for February 17.
The teens are all students at an alternative school in the Upper Darby School District.