Ok, so I've created project with latest SDK and got the same error.
stderr[
D:\Projects\Test_google\Temp\gradleOut\mopub\build\intermediates\bundles\release\aapt\AndroidManifest.xml:80:28-65: AAPT: No resource found that matches the given name (at 'value' with value '@integer/google_play_services_version').
Google plugin builds fine, but when I need to add some other plugin, which uses play services and build with Gradle, I get build errors. In attached project I've added latest google and mopub plugin. Mopub has this meta info in manifest:
<meta-data android:name="com.google.android.gms.version" android:value="@integer/google_play_services_version"/>
which causes problems, but mopub team claims that they've done everything according to google specifications, so the problem is on google's side