The one with the more powerful wand wins. End of.
The one with the fastest broomstick wins. End of.
The tortoise wins. So there.
(In cartoon circles it is always the Roadrunner that wins).
Generally any non-magical species, especially given there are plenty of witches and wizards who feel such types are there for them to exploit. Sadly this is usually as ingredients for spells. There are lots of half blind newts in the magical world... (incidentally why is it only eye of newt, singular? Wouldn't both eyes make more sense?).