When I am adding admob pro plugin to cordova it is not automatically fetching google play services. I tried to install google play servives manually before installing admob pro, then on running the build it is showing error that it cannot locate symbol files.
If you use Cordova AdMobPro plugin, then as mentioned in the plugin documentation you gotta install some extras which include Android Support Library, Android Support Repository and Google Play Services too using Android SDK Manager to avoid build errors.
Also to avoid build errors with following error message "Multiple dex files define Lcom/google/...", you gotta avoid duplication of google-play-services.jar as mentioned in official FAQs.
Please check out this link for more info. Hope it helps.