Yoyo. There are more articles/resources available than the below, but most appear to be older. To avoid the pain of upgrading finding things broken, I would try one of these. They're more recent.
- https://www.youtube.com/user/CodersGuide/videos (series on PhoneGap + Material Design using Polymer)
- https://www.youtube.com/watch?v=XL8NG-_Q4ds (Using Polymer with Cordova)
- https://github.com/infomofo/cordova-polymer-template (Cordova Template for working with Polymer - last year, so probably requires an update)
- https://github.com/MobileChromeApps/mobile-chrome-apps (This lets you use cross-walk (on Android) as the WebView, which is significantly faster. Worth trying for your Polymer app if you're targeting hybrid)