The main problem here is properly paying your dues on monetization. If Nintendo sells you a $10 IAP on your Android, Apple is going to want its $3 to provide that content on your iPhone.
I thought the way it worked is: - User buys game on 3DS, links to their Nintendo account, can play on 3DS, iOS, and Android. Nintendo gets $10. - User buys game on iOS, links to their Nintendo account, can play on 3DS, iOS, and Android. Apple gets $3, Nintendo gets $7 - User buys game on Android, links to their Nintendo account, can play on 3DS, iOS, and Android. Google gets $3, Nintendo gets $7