Archenemies: Yami Yugi and Yami Bakura

Yami Bakura is the perfect archenemy to Yami Yugi, in my opinion, because he is everything that Yugi isn't.

Yami Yugi is good, Yami Bakura is evil.
Yami Yugi wins a lot except a few, Yami Bakura loses a lot except for a few
Yami Yugi is good to his host, Bakura is mean to his host.
Yugi is nice to allies, Bakura betrays his allies