Some users are arguing that the lion would be dominant; they argue that the lion's instinct of defending its pride makes it more suitable for fighting. This is partly true; since its purpose in life is to fight (and reproduce of course), the male lion should be a better fighter. Yet all the other cats are also involved in fighting: female jaguars are known to attack anything that comes close to her cubs, and this includes the father of the little cubs himself; also male tigers are known to fight until death over territory. And what people do not realize is that while the lion rarely hunts (females hunt just about 98% of the time), all the other cats must hunt their own food. Leopards focus on small and medium sized prey to avoid competition; however jaguars and snow leopards are at the top of the food chain wherever they live: they will hunt dangerous prey such as crocodiles, snakes, and tapirs in the case of the jaguar; and yak in the case of the snow leopard. Tigers are a special case as in some areas they must compete against bears for food; yet they still hunt big prey such as buffaloes. If you ever watch NatGeo you will see that it takes three lions to kill a buffaloe while a tiger must kill it alone, and by the way Asian buffaloes are bigger and more dangerous than African buffaloes. Bottom line: the common thought that a lion is a better fighter than any cat is just a myth.
Now finally what would happen if these five cats were the same size and met? Usually cats do not risk to fight, they rather choose intimidation. Well in this case the Leopard and the Snow Leopard would probably retreat; although all cats are the same size, they do not know this, and given the Leopards' skinny and weak looks, they would probably be intimidated by the more robust lion, tiger, and jaguar. They are all the same size, but the lion's mane makes it seem bigger: therefore it could actually scare off the two other cats. This would not happen though because the jaguar has a robust look, and a supersized jaguar would even look bigger and more robust. The result is that the jaguar would be the one intimidating the other cats. Now if we just assume that they are going to fight: the lion's mane would protect him against severe damage from most cats, yet the jaguar's bite could crash a lion's head easily. Bottom line: if we put them to fight one by one, the jaguar kills them all; if they all fight at the same time then the lion could be the winner, as the jaguar may be killed by a coalition of two other cats.