Okay, this is how I think it will go, assuming the groups try to face off against old rivals from the start:
Vampires defeat Werewolves because of their quickness and intelligence.
Wizards defeat Orcs because of their magicz.
Giants defeat Dwarves because even though they are good, the giants are big and ultimately too strong to take down.
Ninjas defeat Pirates because when it comes down to it, pirates are drunks and the ninjas can use their array of weaponry to defeat the mostly short-range or inaccurate weapons of the pirates.
Cyborgs and Elves draw. These two factions sort of get stuck fighting because of the other frays. The skills of both work equally well against each other and they are forced to move on to the next opponents.
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This leaves: Vampires, Wizards, Giants, Ninjas, Cyborgs, and Elves.
Wizards pick up where the dwarves left off and vanquish the Giants because they are so much more clever and have a ton of spells at their disposal.
Cyborgs decimate the Ninjas because it doesn't matter how sneaky you are against thermal scanning and futuristic weaponry.
Elves draw again against the Vampires. Both are quick, agile, and fierce fighters. Fangs meet neck and silver-tipped arrows meet soulless heart. Both take a heavy hit from the combat, but both still move on.
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Remaining: Vampires, Wizards, Cyborgs, and Elves
At this point in the battle, good turns on good and evil turns on evil.
The Wizards face off against the Elves. While the elves are fast and can dodge many spells, they can't dodge them all. Their arrows are turned into ribbons as they thwip toward their opponents. Wizards, in the end, prevail.
The Vampires find no worthy flesh among the Cyborgs, so they cannot turn their enemies as they did before. However, the strength and destructive power of the cyborgs comes to their advantage as they shred the vampire ranks. Cyborgs win.
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The Final Showdown: Wizards and Cyborgs
Starting off, the Cyborgs feel they have a huge advantage against the old conjurers and word-speakers. However, their arrogance turns to shame as the Wizards collectively call upon a force that means doom for the cyborgs: lightning. With their hard-wired systems shut down, they can't use their own equipment and are left to suffer the wrath of the Wizards.
Wizards triumph.
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