Mispati and Montgomery will be sentenced on November 22.
The identities of other people the men shared the drugs with is suppressed.
The change in plea comes after fashion designer Christopher Lay earlier pleaded guilty to 17 cocaine-related charges.
McLellan is a business manager who also appeared in an advertising campaign for Fonterra's Anchor brand, while Bhikoo is a hairdresser.
Mispati is a professional kickboxer and personal trainer, and Montgomery is a clothing distributor.
The men were arrested as part of Operation Ceviche, which led to the seizure of 760g of cocaine, worth $300,000, and $81,000 cash in late August last year.
The covert investigation by the National Organised Crime Group initially focused on Anthony "Ants" Nansen, a senior patched member of the Hells Angels motorcycle gang.
Bhikoo's lawyer Ron Mansfield provided the Herald with a statement from his client, which said the cocaine was "heavily cut" and used between close friends.
"I had access to the drug through another person I knew and would get it and then others would get it off me. I was not some big wholesale or street dealer," the statement said.
"At the time, we were all using the drug in our social circle. It started out being social use only, but I accept we let it get a bit out of control. We have all cleaned up our acts. Things are clearer and better now.
"I have addressed my use of controlled drugs now and I am focused on my career. I regret this time and the lifestyle we had. In particular I regret the negative influence the supply of the drug has had on others."
