The resolution happened after Christchurch District Court Judge Gerard Lynch had ruled out Crown charges against each of the men that they had participated in an organised criminal group.
After accepting all the pleas, Judge Lynch thanked the gang members "for how you conducted yourselves" in court.
No summary of facts for the gang brawl has yet been finalised, but Crown prosecutor Mitch McClenaghan said it would be ready for June 1 when another four men charged will appear in court.
The four others were not at court today for various reasons - non-appearances, hospitalisation, and illness.
Some facing only assault charges may be sentenced on June 1, but most of those who have pleaded guilty to more serious charges have been remanded on bail for sentencing on September 28.
Those who pleaded guilty today were: Wilson Koro Ruawhare, Richard Moana Edwards, Harley Zeke Tapine, Baden Kenneth Clunie, Joshua Owen Wiley, Dukie Montgomery, Vincent Raymond Eric Olsen, Dylan Rudd Stuart, Zane Joseph Brooker, Steven James Wood, and Hendrix Joshua Nathaniel Crichton-Weke-Tuhimata.
They have admitted various charges of assault, assault with intent to injure, and injuring with intent to injure.