i saw the video on youtube. apparently this is a legit strategy. have cloud fairly highly level with omnislash ready to go. ALL the materia he can equip has to be linkable for this to work. MASTER levels required. Pair up Mime and counter in all slots. Cloud should use omnislash repeatedly until emerald dies. In the video i think he used it 7 times in a row.

The ruby strategy video is also intereting. The only Conscious character used was barret. i am not sure the materia combo but its sort of the same as the emerald trick. one of his limits that hits repeatedly does 1 dmg. barrets health regens upto 7777 then all his hits do 7777dmg.

I am personally going to test both these theories in game to make sure my information is accurate and the videos werent tampered with