Whoever made the first mistake
T. rex would win. Deinonychus was relatively small, small enough that a T. rex would be able to kill one in a single bite.
gigantosaurus
It depends on the size and gender of each one.
There is no doubt that the pack of pirahnas would win, they are more agressive and have larger teeth
I would win
just one argentinosaurus the pack of t-rex would simply just win
The wolves would win easily but they may not be able to catch the greyhounds.
i'd say tyrannosaurus because it had a much stronger bite force than giganotosaurus did. though it's possible for giganotosaurus to beat t-rex. but the might not have fought because t-rex lived in north America and g-rex(giganotosaurus) lived in south America. g-rex was a pack hunter. so 1 t-rex wouldn't stand a chance against a pack of g-rexes.
pack of wolves
I would say the raptors because they are bigger and have bigger teeth.
Giganotosaurus was 43 feet long and weighed somewhere between 6.5 and 14 tons. Allosaurus was 32 feet long maximum and weighed somewhere between 1 and 4.5 tons. Thus, Giganotosaurus was far larger, and thus the only hope for an Allosaurus fighting a Giganotosaurus would be to flee. Note that Allosaurus never would have encountered Giganotosaurus, as the former died out about 53 million years before the latter evolved, and they didn't even live on the same continents.
Pack of Timber Wolves will surely win the fight