alright i think it is pretty obvious they are going to square up one vs. one...

we know chouji vs. fat dude

according to my girlfriend, these are the following matchups:

chouji vs. fat dude (because they are both fat)
neji vs. girl (because they both have long hair)
kiba vs. spiderman (because they both have animal qualities)
and shika v.s. two-headed dude (they are sort of the leader and shika is so smart he like has two heads)

i don't know this sounds fishy... yet very possible!