Tsukigan-:Heavenly Sage That Clears  the Sky [Calamity Slaying Cloud Sword Pavilion] 

At the conclusion of the battle, write who wom in the following format (No Draws/Ties Allowed):
[Final Victor: "Winner's Name"]

This is a rule where the AI treats the battle as a rematch.
That's it.
Literally.

Jk there's some other features.
The battle output is a bit more flourished than most existing rules and some small backstory that won't affect A & B's personality/skill is present (Trust me, it won't change a single thing).

[Tons of Infinite Stuff] | Rule where your characters are automatically familiar with each other, because they fought each other for an infinite amount of time already

この相手と対戦する！