How to change the vibrate pattern for Messenger and GroupMe? I have the iPhone 6s and I do not like the default Facebook Messenger and GroupMe vibrate pattern, whereas I like the default one provided by Apple. Is there a way to change the vibration for non-native iOS apps on the new iPhones / iOS 9?
Apps specify their own vibration patterns, and unless they offer a way to customize it in-app, that's what you are stuck with. Sadly, most apps do not.

The same goes for notification sounds, with most apps only offering an on/off switch while the app is open (iOS controls the on/off switch for global notification sounds while the app is closed).