Brett Russell has been charged with 80 offences, including dangerous driving causing serious injury and reckless conduct endangering life, over the September 2022 crash.
The bus, from Loreto College Ballarat, was on its way to the airport to take the children on the trip of a lifetime to NASA space camp in the US, the court was told previously.
Russell is accused of ignoring warning signs to brake and rear-ending the school bus, forcing it to roll down an embankment off the Western Highway at Pentland Hills, west of Melbourne, on September 21.
Thirty-two people were injured in the crash, including 27 school students, four teachers and the bus driver, with injuries ranging from bruises to an almost total foot amputation.
Russell, who is on bail, appeared via video link for a hearing at Melbourne Magistrates Court on Thursday, where his lawyer requested eight children give evidence about the seriousness of their injuries.
Barrister John Lavery applied for the children and some medical specialists to be called as witnesses at a contested hearing later this year.
"With two of the witnesses, Your Honour, there is no medical evidence," he told the court.
"On the issue of serious injury for two of the complainants, the only evidence of any injury comes from those complainants."
Another child's injuries had been assessed as not meeting the criteria for serious injury by a hospital trauma registrar, he said, adding that Russell faced three serious injury charges for that child.
"The serious injury allegations come from a physical therapist," Mr Lavery said.
The prosecution has opposed the application and said they were awaiting evidence from treating doctors, including physician's notes, to prove all of the injuries.
Russell was initially charged with 46 offences, but that was increased to 80 charges by prosecutors at a hearing in July.
The hearing before Magistrate Peter Reardon continues.
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