Well, if the "leaked" set list that's been circulating around isn't full of shit, there are 3 "battles":
13) “Volume Battle” – Kangta, Luna, Yesung, Jonghyun, Taeyeon, Zhang Li Yin
14) “Dance Battle” – BoA, Yunho, Yuri, Eunhyuk, Hyoyeon, Taemin
15) “BATTLE SPECIAL” – Kangta, Luna, Yesung, Jonghyun, Taeyeon, Zhang Li Yin, BoA, Yunho, Yuri, Eunhyuk, Hyoyeon, Taemin
Granted, the set list could be a farce, and they have plenty of time to change it, but I hope these 3 performances make it into all the concerts.