I also have a problem with cordova-plugin-admobpro after updating to API 35 - rewarded video is not shown. It seems that the plugin is relates to an outdated SDK version (20.4.0):
https://developers.google.com/admob/android/deprecation
I tried specifying more recent versions, such as 23.2.0, with the following command:
cordova plugin add cordova-plugin-admobpro --save --variable PLAY_SERVICES_VERSION=23.2.0 --variable ADMOB_ANDROID_APP_ID="ca-app-pub-***~***"
Unfortunately, it doesn’t appear to work with these newer versions, if I understand correctly.
I sent the letter to the author - Raymond Xie (floatinghotpot), waiting for feedback. If he doesn't answer, I'll try other projects, but cordova-plugin-admobpro was the most convenient IMHO: