I switch to remote play on my Vita quite often and to emote you press left on the Dpad and circle/square/triangle/x to use each emote. So it would be simple to have emotes like that on the DS4 or Xbox One controller. It would then free up the Dpad and be great to cycle weapons on 3 of the Dpad presses - something like Left for primaries, Up for special weapons and Right for heavies. Down would then be free to cycle through syntheses.