One thing my brother and I learned a while ago... Akinator seems to know practically nothing about New Zealand's history, especially with regard to the Maori people. Were able to reliably stump him in this area.
I beat it by using an obscure character that briefly appears twice in a series without many known details.
I've beaten him plenty of times, but the trick with the mobile version is that they reward you if the character's obscure enough that no one's asked in a while, but not so obscure that he can't get it in the first round. If it goes into 2+ rounds, they tell you what the reward would have been if he'd gotten it in the first.
Chairslut of the Funky Shack Institute of Genital Philosophy