Mobile Platform is more and more important and popular. So we can not only consider traditional platforms for our Google AdSense.
The best solution is that let AdSense be able to display on both of Desktop and Mobile platforms. There were some people had their solutions, or made some plugins. Actually, we do not need to do extra works, Google has considered it for us. We just use the AdSense scripts directly.
Either old style AdSense or new style AdSense, Google has made them (or part of them) worked on multiple platforms.
For old style AdSense, the size of 300×250, 250×250, 200×200 support desktop and mobile, Please check Google ad sizes Guide:
For new style AdSense, Google has a new style ad unit named Responsive ad unit. by now it is a Beta version.
Responsive web design allows you to dynamically control the presentation of your website according to the properties of the screen/device that it’s being viewed on. By using a responsive ad unit, you can control the size of the ads on your page, in line with how you control the layout of the rest of your page across devices.
Please see details at this page.