A fourth teenager has been charged in connection with a "sustained" attack on a man at a tram stop, police said.
The victim, 49, was knocked unconscious at the Freehold stop in Chadderton, Oldham, on 8 March, and suffered serious injuries.
A boy, 16, who cannot be named, has been charged with attempted murder and is due at Tameside Magistrates' Court.
Two males, 15, have already been charged with attempted murder, assault and attempted assault.
Another boy the same age is accused of assault and attempted assault.