getting 100%?

ok so i've completed the story mode for each character and noticed that it was not at 100%, which was not surprising, so i have since went through it with a couple of characters again and made sure to defeat every single battle piece i seen....and still not at 100%

what other things should i be doing?

also to get the full benefit of the story should i complete shade impulse with each character or is doing it with just one enough?

thanks guys