Ok, so the more I look into it, the more I believe that Kangaskhan is only available in Australia. Not long ago there was a news article saying that a chap called Jeremy Lai has caught all 141 Pokemon available in NZ. I have 136 and am missing Porygon, Omanyte and it’s evolution, Machamp and Charizard, which will take me to 141 Pokemon.
Additionally none of the people in the forums (this or any other) are saying that they’ve seen anyone who has caught a Kangaskhan in NZ.
It’s my firm belief that Kangaskhan is currently only available in Australia.