What defense does chouji have against tail chaser? Also people seem to forget that kiba has always been either faster or the same speed as weights-off lee. With that kind of speed dodging chouji shouldn't be to much of a hassle since he doesn't have his team as support.
IMO chouji's battle style is to linear and simplistic to win. He basically serves as the attack that distracts someone as Ino or Shika trap them. His solo strategy doesn't change much either he just gets bigger. Kiba on the other hand has a lot more in the way of traps and tool use (see edit).
Edit: also chouji can't fight if blinded by either smoke bombs, flash bangs or dynamic marking - whilst kiba excels under these conditions. Akamaru has also been shown to set paper bomb traps independent of kiba as well as kiba himself setting exploding kunai traps in the form of a fake akamaru.