How do you migrate this game to a new Android tablet? On the new tablet it will not link the Nintendo account, stating "the nintendo account you selected has already been linked to another smart device".
EDIT: Don't worry, turns out that the only way it will link is to ensure you're already signed into your Nintendo Account in your browser BEFORE you start the game for the first time, and then you link it at the absolute very first opportunity within the game. It doesn't work if you try to link it at any other time, even if you are on the title screen and you try to link it there.
If the error message comes up, then you have no choice but to erase the app data and start again.