The platform used in Polaris snowmobiles since 2016 is AXYS.
AXYS is a Polaris chassis and platform family designed to improve rider balance, control, response, and weight distribution. Polaris first introduced AXYS for flatland trail and crossover models in the 2015 model year, then expanded it to the mountain-focused RMK line for 2016. That rollout is why the question commonly associates AXYS with 2016 Polaris snowmobiles.
AXYS was not a model name or an engine designation. RMK identifies Polaris mountain sleds, while IQ and Pro-Ride refer to earlier Polaris chassis or platform families. The distinction matters because several model names could appear on an AXYS sled: RMK, RUSH, Switchback, and others.
The platform later gave way to Polaris’s MATRYX architecture, introduced for the 2021 model year in mountain sleds. Thus, “since 2016” is best understood as the beginning of AXYS’s major mountain-snowmobile era, not a claim that every later Polaris sled still uses it.