Natzke won the class, but Cohen Chase and Wyatt Chase finished second and third respectively.
Most recently, Cohen capped off his year with fourth overall finish in the senior MX2 class at the big annual Whakatane Summercross.
Meanwhile, his younger brother Wyatt won the 15-16 years' 125cc motocross crown at the three-day New Zealand Junior Motocross Championships near Te Kuiti in April, then compiled a hat-trick of wins in the 15-18 years' 125cc class at the Secondary Schools' Nationals in September, before leaving the country to race, finishing runner-up in the 15 years' 125cc class at the Australian nationals.
He was untouchable in the 15-16 years' 125cc class, winning all three races, at day one of Taupo's annual MX Fest event in October and then took his Total BikesportNZ.com YZ125 bike to win the all-comers Champion of Champions feature race. Wyatt followed that up with another sensational performance in winning the senior 125cc class the following day.
Most recently, he won the junior 16-17 years 125cc class, ahead of fellow Yamaha rider Ollie Ayre, from Havelock North, at day one of the big annual Whakatane Summercross and finished runner-up, behind Cambridge's Trent Collins, in the Youth MX class on day two of the weekend just gone.
"The first day at Whakatane was great ... I got three holeshots and three wins," said Wyatt Chase.
"Even though I was a wee way in front, I still pushed myself hard, just to see if I could better my laps times.
"The next day was tougher because I was on a 125cc two-stroke and Trent (Collins) was on a 250cc four-stroke bike. Each time I had to fight through the traffic and ran out of time before I could make a challenge on Trent. I was matching his lap times, so that was pleasing.
"I've got some unfinished business to do in 2016. I crashed out of the 2015 senior 125cc nationals, at round one in February, and so I'd like to win that.
"But both Cohen and I will also be racing the Valley Motocross Championships at Patetonga on January 10, followed by the New Zealand Motocross GP at Woodville at the end of January, before we look at possibly racing overseas. I can't be specific about details yet, but planning for that is underway."