Lord Voldemort from Harry Potter
Pein from Naruto.
Battle takes place in front of empty Hogwarts. Lord voldemort is standing there alone.
No prior knowledge, no preparation.
Magical energy is similar to chakra for the battle.
Pein has sent the six paths to get rid of voldemort. Feats from manga/anime/movie/books allowed.
Win via death, ko, Bfr, making unable to fight.