In the remaining championship class, the Junior Lites, it had looked like Hamilton's Nicholas Westgate would take charge after winning the first two of three races on the night.
However, Czech Republic rider Julius Mikula took the win in the final and Westgate was left in seventh place.
Townley, who was national SX1 champion in 2016 but a non-starter last season, battled early on with fast-starting Taupō rider Cohen Chase, but once in front, Townley was never threatened.
Nelson's Reece Walker took the third spot on the night's SX1 podium with a solid 3-2-3 scorecard.
Natzke's three wins from three starts at Tokoroa then pushed his advantage out from three points to 15 over Martens, who managed 3-3-2 at Tokoroa, while Mangakino's Maximus Purvis secured third with a 4-2-3 scorecard.
Motorcycling New Zealand Supercross co-ordinator Noel May was thrilled with the rider turnout at Tokoroa.
"It was pretty awesome. About 18 months ago we had a meeting in Taupō and came up with a strategic plan to build a pathway for the riders, rebuilding the juniors, so that they feed into the seniors in the future and what we saw here at Tokoroa absolutely kick-started that," May said.
"Entry numbers were up 40 per cent on last year and we had more support classes here too. I want to tip my hat to the Junior Lites and Junior 250s too for turning out in force, and then having a dozen riders entered in SX2 and 10 in SX1 was great too.
"The junior 250s will kick on up into the SX2 class really soon, so that's positive news going forward."
The riders now head to the South Island for the final round of the series, to be hosted by the Southland Motorcycle Club on December 15.
- Supplied content