Did the Romans Keep Any Records of Their Favorite Animal Combatants?

Question

Which animal verse animal contest were the most popular? What Did they consider through testing to be the toughest animal?

Answer 1

They didn't have animals fight each other, they did executions 'res bestia', which meant using animals for capital punishment.

Lions would have been easier to find for this than you think, because at that time some still ranged in the Tunisia area, and a smaller version lived

in the Balkans (north of Greece).  Other than that, wolves would have been the easiest to find.  So, probably wolves or lions.