The alleged gunman, a 28-year-old Australian man, faces 50 murder charges and 39 attempted murder charges.
Police have said other charges are still under consideration.
On Friday at the High Court in Christchurch, Justice Cameron Mander ordered mental health reports to explore whether the man, who had been living in Dunedin, is mentally fit to enter pleas to the charges.
The judge stressed that the move was "normal procedure" and an "entirely ordinary and regular step" to be taken at this stage of the judicial process.
The Crown also sought an interim suppression order for the victims relating to the 39 attempted murder charges.
Justice Mander granted the order – which was not opposed by the accused's new defence lawyers Shane Tait and Jonathan Hudson – on the grounds of undue hardship.
Charging documents lodged with the court only refer to the 39 attempted murder victims by alphabetical-numerical numbers, starting with "W001" and ending with "W039".
The accused has been remanded in custody and is due to reappear in court on June 14.