Jade was so pissed at his loss in Godlike to Yuna, that he decided to control Sara yet again and win some dignity!
Well, Sara did win the fight...except it was later discovered that Jade's actions played a role in, and due to some very loosely defined guidelines, it was declared interference, and the match was ruled in Canas' favor in the end.
So what happened to Jade? Well, lets just say Yuna wasn't exactly pleased that he was interfering in a middle match while he was supposed to be polishing Tidus and Wakka's blitz trophies, and decided to assign him to be Rikku's personal servant for a week as a punishment.
While Jade was even less happy about this, Rikku seems to be having a ball with it. After doing her little stint in FFX-2, she thinks it's long past time that she got a bit of male fanservice to make up for it, and as such, Jade has mostly been doing things like carrying Rikku's shopping bags while wearing a variety of fanservicey outfits.
Moral of the story: Cheaters never prosper
Moral of the story #2: They really don't prosper when there's absolutely no damn benefit FOR cheating to begin with.