For people who don't know, Aura Sphere glitch it's using Aura Sphere against some of Drasna's Pokemon will cause a thick black horizontal line with vertical black bars below it to briefly cover part of the upper screen. Against her Dragalge it will appear towards the bottom of the screen; against her Druddigon it will appear in the center of the screen.
1 - Yes.
2 - No.
3 - Now what can causes it? I have been researching and found that it MAY be caused by a glitch in the VFX algorithm. I don't know what is that, but it may be a 3DS system that works for the visual effects and it can be not working in conjunction with Drasna's battle, making it glitch.
4 - I don't think so, since the glitch was only been found at Drasna battle, I think you can't find it any other place.
Also I found another explanation for what may cause it..
At the beginning of the fifteenth second in the video, we see Drasna's Pokémon take the hit from Aura Sphere. Aura Sphere is programmed in such a way as to cause the field to temporary appear to be yellow with no details. At the middle of the fifteenth second, after the Aura Sphere object has made contact, Drasna's Pokémon is mostly done recoiling from the attack when most of its model is suddenly covered obscured by yellow. The only available details at this moment is the head, part of the left wing, the left leg which is slightly faded, and the tail which is also faded. Towards the end of the fifteenth second, the yellow field returns to the normal field, which now shows the fence that covers the rightmost incense emitter is now in the foreground, while the battle is the background. Thus, the camera angle for Aura Sphere causes an issue with the field, but it is only after Aura Sphere hits since the animation of Aura Sphere ignores the fence until that point. I would like to note that there either the field for Drasna's Chamber is different from the other fields for the Elite Four or that no one has checked to see if the other fields cause this same issue.
Hope this helps.