Challenge description:
http://www.femlob.com/redir/ff10nsgnsno/

I went shopping after I'd beaten Spectral Keeper, as I was kind of running short on a few things.

This is where the challenge does a 180. I did the grinding and customizing tour from hell (during which I cheated by adding Bribe to Kimarhi; it's against the rules, but the grinding had already taken half of forever. Hey, sue me), and ended up with a Faerie Bracer for Auron and an Alert Targe and Talisman for Rikku. The Alert Targe is simply Sleepproof, so that I don't have to muck about with Star Curtains during Yunalesca's first phase. Auron and Rikku, however, come packing Deathproof, Confuseproof and Zombieproof. That setup makes you practically invincible. Emphasis on practically, as you can see at the end of the second video. One critical hit at a bad moment and you're going to have to wait until the next Mega Death before you can get Rikku back into the fray.