Kylo Ren vs Shin Uchiha
Both are immature, sorta pathetic villains the idolize noteworthy bad guys in their own worlds(Vader and Itachi) and have dedicated themselves to fulfilling their work in spite of what their heroes actually believed when they died.
Round 1: Shin goes to assassinate Kylo on a whim. Snoke, foreseeing this, sends Kylo into the trap for training. The fight takes place on Endor, where Ren is looking for Vader's helmet. Both are alone(Shin gets his little creature buddy though).
Round 2: Same as above except Kylo gets 15 Storm Troopers+Phasma while Shin gets 15 mini-Shins and the one big Shin clone.
Bonus Round: Rey vs Sarada. Takes place in Shin's home dimension and this is Rey at the end of the movie.