Head of Product (Allo and Duo) at Google, Amit Fulay posted this information in form of a tweet on Twitter saying;
Trying out our new polling feature in Google Allo, let's go Gozanga. #GoogleAllo
However, you can only create poll for yes and no questions, this means that you cannot create custom poll at this time. So to create poll, just type @yesno then followed by your question and the poll will be created successfully.