Supported Media
Android supports many media formats. For a complete list check the Android MediaPlayer documentation here: https://developer.android.com/guide/appendix/media-formats.html and the ExoPlayer documentation here: https://google.github.io/ExoPlayer/supported-formats.html
HEVC (H.265) support was officially added in Android 5.0 (Lollipop) but only as a software decoding implementation on older devices.
We have found that using GearVR on Samsung Galaxy S6 and S7 that H.265 codec works best, with a resolution of 3840x1920 at 30fps, or 2048x2048 at 60fps.
A list of media-player related Android chipsets and which formats they support for hardware decoding: http://kodi.wiki/view/Android_hardware