Any softwood needs to be treated for use as decking except macrocarpa heartwood. Its natural durability can be sufficient for this purpose (although its durability is unreliable in moderate-high decay hazard situations, and occasional failures may occur within 10-15 years).
Most hardwood is naturally durable and resists all kinds of wear and tear. Locally grown eucalypts can be suitable for decking.
The Decking How-to-build guide suggests treated Radiata Pine.