The classic question.
Rules: This is a fight in an arena, you are unarmed, you cannot leave the arena until every other animal is dead, and while the animals are as intelligent as normal they do understand that they’re fighting you and will try to do so, they won’t just run away.
100 duck sized horses. I'd punt them carefully one by one. And what could they even do, try to bite me? Give me mild kicks and then fall over? I'd just have to wear thick boots and motorcycle pants.
I have no chance against a 400kg duck.