I'm going to disagree with that. In my opinion, the Ceratosaurus would win. Estimates for Ceratosaurus magnicornis weight have been over 450 Kilograms, 700 Kilograms, and 980 Kilograms, and the most recent estimates I can find for the average Allosaurus fragilis are about 700 Kilograms as well. If we just use the middle-most weight in there to be fair, this means that the Ceratosaurus would still be a fair bit heavier than a small Allosaurus fragilis, while still being slightly more agile just due to being shorter in length. As for the running faster, that wouldn't be super important in most altercations. If this is simply a minor territorial battle, basing this off of Tyrannosaur intraspecific combat, they'd most likely bite each other on the faces, which would lend to Ceratosaurus' favor due to its enormous teeth and its superior bulk, giving it the edge in the battle. The Allosaurus' smaller teeth wouldn't be as good for this kind of situation, and the crests of the Ceratosaurus give it minor protection of it doing too much damage to the skull. In a fight to the death, the speed won't matter much because the Ceratosaurus' shorter length would make it slightly more agile or on par with it in terms of agility, so it wouldn't be able to run around the Ceratosaurus. Even if it did, the Ceratosaurus' back osteoderms would give some good protection against the Allosaurus' attacks to the back/spine, and it can muscle off the Allosaurus and begin to melee it. Due to its higher weight, it has the advantage there. Not only that, due to its shorter height in this case, Ceratosaurus would have the advantage of having a good shot at the Allosaurus' long, exposed neck, something its large, slashing teeth can take perfect advantage of. Allosaurus, being larger, has the disadvantage of having to bite down onto the Ceratosaurus from above, which is bad in this case because Ceratosaurus has osteoderms on its back to protect it from attacks like these.
The main problem would be Allosaurus' claws, but I doubt that the arms could purely muscle off a heavier animal, and tearing it off the neck would do more damage to its neck in the long run. Not to mention, the arms won't be as good against Cerato's shorter, thicker neck compared to the enormous teeth or Cerato against Allo's longer and thinner neck.
As for the pack hunting, I don't think there's much or any actual evidence of pack hunting in Allosaurs, and it's just a theory. I could be wrong, and if I am, can you show me a paper detailing the evidence or something like that? Thanks.
Even assuming higher intelligence, in a minor territory battle it won't make much difference, and a melee confrontation it won't be enough to give it an edge against a more robust creature.
