The left and right bumper buttons seem to do nothing, so why aren't they used to cycle between primary (offensive) and secondary (defensive) abilities? (darkstation.com)
There is also a lock - on: pressing the left bumper button will rotate the camera to centre on the largest enemy in the area, which does make combat substantially easier. (darkstation.com)
Holding the top right bumper button will let you move both characters simultaneously. (en.softonic.com)