There is a new Android Studio update: https://sites.google.com/a/android.com/tools/recent/androidstudio030released
The link says:
The improved per
This is a late response, but in case anybody's run into a problem of the gradle version in their ionic project being overwritten by an older one by AS, just remove the android platform from your ionic project and then re-add it. Evidently, installing Gradle is part of that command, so you'll overwrite the overwrite, and get the version you need to run ionic build android from within your Ionic project's root directory.
Although, WARNING: Removing the Android platform, and then re-installing it, might wipe the splashscreens and icons that you'd had in your resources folder. And by "might," I mean that it's happened every time that I've done it (which makes sense, since the resources folder is inside of the android folder that you're removing/re-intalling). Perhaps a more eloquent command line input could reinstall the android platform while leaving the resources folder alone, but, in any case, make sure to copy the directory with your custom splashscreens and icons to a new one before running the re-install.