The criteria they gave is that; the android device must be 6.0 marshmallow and higher.
Google Assistant help you with specific things like reminding you of your flight details, telling you if you need to dress for rain, and even control your smart home. It’s all done in conversational tone, so you can string questions and responses together as if you’re talking to an actual assistant.
Yippie good news you no longer need to buy pixel, Google Home, Android Wear 2.0 watch, use Allo, or buy any of the newest smartphones to get Google Assistant. Google has announced that; the google assistant will be available to android phones this week.