Pokémon Master (Kinda)
My favorite would gotta be Ash vs Paul and my least favorite would be Ash vs Cameron
Unpredictable? Ha, what a joke. By the time of the League battle, it was obvious the writers had zero interest in giving Paul meaningful consequences for his actions (He still had Chimchar and blamed it for losing during his his battle with Cynthia, which he later abandoned like the coward he is [and for which the writers horribly had Ash defend his cowardice], and the loss to Brandon is meaningless, as Ash lost twice and nearly lost a third time to him), so they let him destroy Ash's team with only 2 Pokemon. A damn meaningful consequence would have been having any, if not most, of Paul's Pokemon be disloyal for his constant abuse of them.I think the reason people liked the Ash vs Paul battle was because of how unpredictable it was and it had lots of strategy.