Trans Tasman Aust to NZ Air NZ & Virgin codeshare many flights. No Business (J/C) on some of these. Air NZ have gone down market removing C from many A320 aircraft. But Air NZ does have a full international B777 on MEL-AKL route (or did last Xmas)

Emirates also fly trans Tasman with competitive c/J fares and also first class

On Trans Tasman flights check very carefully what aircraft operates the sector: can be a vast difference (but same $$$). Many flights per day