From GF
"Granted, it's like 95% story and 5% playing, but still. It's a bit nonintuitive to get to, but it's there:
After you beat a chapter in the story, you unlock a "Report" in the report section (which you can access from where you choose which story to play through). As you scroll through the reports, you'll see certain phrases highlighted in blue. If you press Square while on one of these pages, you'll be given the option to select the blue phrase. Doing so will take you to a cutscene, or (in rare instances) a party battle. I'm not sure if you need to have purchased the villains to do this (in my game I already had before I stumbled onto this).
I've gotten through the first four reports and started the fifth report, and have played as Kuja, Terra, and Sephiroth so far. Also, I watched lots of cutscenes in Japanese, and understand none.
Haven't finished 013 story yet, but as the report page shows lots more spaces for reports to be unlocked, I can only assume that finishing chapters in 013 will also unlock reports in which you can continue to watch/play the story from Chaos characters' perspectives."
So yeah.