Her rescue of the outnumbered Dawn and Brock. Followed up by taking out Goon's two Scizor with one hiteach. Sealed by blowing them all away with a single well-placed Night Burst.
After Kodai realized the illusion, he electrocutes Zoroark with his claw. Zoroark then grabs the claw, overpowers it with aDARK PULSE, then tears what remains off her neck. In addition, she only showed how much she was affected until AFTER Kodai flees.
As she suffers her temporary death, she brings Kodai down with one last illusion.
Zoroark makes every other Pokemon in the series look like they're made of cardboard, and is a member of a species of Glass Cannons. Bad. Ass.
When Zorua-disguised-as-Celebi was exposed, Karl's Bronzor (who had tagged along with him) uses Extrasensory on Kodai's truck, smashing it against a tree. Sure Kodai got out before impact, but he actually messed with the Big Bad instead of just floating there. In addition, being taken down afterward enraged Zorua, who then bit his wrist, disabling his Illusion-Canceler and setting up his Humilation Conga.
It also gets a Big Damn Heroes towards the climax, shielding Ash from Kodai's Mismagus with a Reflect.