The father-of-two grew up in Rotorua and left for Australia about six years ago.
An online fundraising page for his family has already raised more than $8000.
Messages of love and support following Mr Diego's death have been posted from people who have donated money overnight.
One said "RIP Diego Condolences to family and friends" and another said "Infectious smile and a sweet heart. Always driven to have a go and to have a laugh."
Mr Hulton's first cousin, Roxanne Brown, set up a Go Fund Me page to raise money for Mr Hulton and his family as they come to terms with the brutal bashing that left him critically injured on Friday night.
The page said the 37-year-old was the "victim of a one punch attack (coward punch)" in a bar at Ellenbrook in Perth.
"We, as a family unit, are devastated and he will not recover from his severe brain injuries. If you would like to make a donation/koha, please follow this link. Every single penny will be given directly to his family to help cover costs," the page said.
Ms Brown said on the page the family thanked everyone for not only the donations, but for the "aroha, care and support" they had shown.
Mr Hulton's cousin Lufa Toleafoa told the Rotorua Daily Post he grew up with Mr Hulton in Ngongotaha and Mamaku.
"We were like brothers. I named him a hard hitter. When he tackled people on the rugby or league fields they never got back up. But there wasn't a violent bone in his body. Everyone loved him. You wouldn't get anyone saying a bad word about him."
Mr Toleafoa said Mr Hulton played league for Pikiao and rugby for Rotoiti, Whakarewarewa and Ngongotaha.
He said he was a saw doctor by trade, always worked and was a "good man".
He said Mr Hulton was the type of man who would try to fix something if he didn't think it was right, and he wasn't surprised he was trying to break up a fight when he got hit.
"He was pretty much a big giant teddy. He wore his heart on his sleeve and just loved life."
Two men have been arrested. Salvatore Raimondi, 32, appeared in the Northbridge Magistrate's Court on Sunday on charges of causing grievous bodily harm to Mr Hulton.
He is also facing a second charge of assault occasioning bodily harm in relation to another victim. He was remanded in custody until his next appearance on February 21.
A second man, also 32, was charged with assault occasioning bodily harm in relation to the second victim.
- To donate to the page go to www.gofundme.com/3cbiu6w
