He denies all allegations against him.
The hearing was adjourned until 2pm when the first complainant would begin giving their evidence.
Pell's legal team had made submissions on that issue to police and to the Director of Public Prosecutions, the barrister added.
Pell was charged past year with multiple prior sexual offenses.
The former Sydney and Melbourne archbishop did not have to attend the previous hearings, but opted to do so, having vowed to clear his name after a two-year investigation led to him being charged on June 29 last year.
Cardinal George Pell has faced court on the first day of a month-long committal hearing to determine whether he will stand trial for alleged historic sexual offences.
"It is a guide to police about how to fairly investigate claims against prominent people", he told Melbourne Magistrates Court on Monday.
Crown prosecutor Mark Gibson SC explained the dog's role is to lie or sit calmly next to a complainant as they give evidence.
At the end of the four-week proceeding, it will be up to Magistrate Belinda Wallington to decide if there is enough evidence for the case to go to trial in the Victorian County Court.
Pell was Archbishop of Sydney before he was promoted to the Vatican as a prefect of the church's economy ministry in 2014. He intends to return to that job once the criminal charges are resolved.
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Pell, 76, is the highest-ranking Catholic official to be accused of sexual offenses.
In its findings handed down in December, the five-year inquiry found Australian institutions "seriously failed" children in their care, with tens of thousands sexually assaulted.
His defence barrister, Robert Richter QC, stated at his first hearing in July past year "Cardinal Pell will plead not guilty to all charges, and will maintain the presumed innocence that he has".
A heavy global media presence is expected to follow the Cardinal outside court throughout the proceedings.
He told Wallington, the magistrate, that he understood the prosecution "has an objection to that support person being a priest, although I can't understand that".
Karen Baxter and her mother Beverley Hastie showed up in support of Pell after he had already entered the courtroom, holding a sign saying: "No trial by media".
Richter said he was fine with the dog, as long as it didn't "make any comment".
"These documents are certainly relevant to the alleged offences", Richter said. "I know they don't suit the prosecution because they're exculpatory [favourable to the defendant], but they're still there and they're in the possession of the police", he said.
The case places both the cardinal and the pope in potentially perilous territory.
Well, due to Pell's own allegedly "catastrophic" actions, the Catholic Church's reputation has taken another big hit. For Francis, they are a threat to his credibility, given that he famously promised a "zero tolerance" policy for sex abuse in the church.