It's debateable if such is needed for those that get apps from the Google Play Store. If you are going outside the store then God help you as any malware laden app will likely tested to get around any titles we know of for anti-malware.
So here I install few apps but always from the play store or the apps we write in house.
What is the Best FREE malware app for Android ? There's so many out there, it's confusing as hell. And is AV absolutely necessary ?