Made a short clip for this one, in no way do you need to use the characters i did, it's just if you've beaten the story and still need this, the awakened characters just do way more damage and it'll go quicker.
In my experience,
you MUST finish them with standard attacks, I was using jutsu's/ultimates/throws and it just did nothing for me. Use a throw to get them against a wall, B,B,B,B...