Receiving messages from androids

An iPad cannot send or receive SMS/MMS messages on its own, even a cellular model. You can only do this on an iPad if you have an iPhone and set it to share messages with your iPad. More info on "continuity":

Use Continuity to connect your Mac, iPhone, iPad, iPod touch, and Apple Watch - Apple Support

If you don’t have an iPhone to pair with it, to use the iPhone’s SMS/MMS carrier service with the iPad, you can use a cross platform internet messaging services like Skype or Google Hangouts.