But Tipene, of Linwood, Christchurch, pleaded guilty to causing grievous bodily harm at Christchurch District Court and yesterday was sentenced to two years and nine months in jail, with reductions for early guilty plea and his youth.
The bus driver was knocked unconscious in the attack, the court heard.
He was taken to hospital by ambulance with cuts to his face, and swelling and bruising to his face and neck.
It later emerged he had a fractured bone in his cheek.
All three were originally granted bail but Harrison was later twice arrested for breaching its conditions.
Today Harrison made an application for electronically-monitored bail at his family's house in Auckland.
He also had a charge of aggravated robbery upgraded to causing grievous bodily harm.
Defence counsel Andrew McKenzie questioned if he should be facing such a serious charge.
Judge Tony Couch rejected the bail application.
Harrison was remanded in custody until July 18 for a pre-trial callover -- the same hearing of the other co-accused, Hamilton, who has also pleaded not guilty and has elected trial by jury.