It was alleged the three were among 18 people who arrived at the victim's home, that several dragged a man outside, and that the man was assaulted as others stood around preventing members of the man's family from going to his aid.
Injuries included a fracture of the skull, burst eardrum, a skull laceration of up to 10cm, and traumatic brain injury.
The first arrests were made as police intercepted the vehicles heading towards Hastings.
The three in the trial admitted to police they had gone to Waimarama, but claimed they were not aware of the purpose of the trip and had not taken part in what happened, Stuff reported.