>>26713186Probably because they're unlikable characters, and it seems like everyone can't list any positive traits about them aside from "douchebag" or "asshole", like you've done just now.
On that note, why do people hate Barry? He was a good rival in my opinion. He was your friend, but he also wanted to give you a challenge, and had the same goals you did in competing in the Pokémon League. Those are definitive traits of a rival, you don't need to have someone be an asshole to you to have the motivation to beat them, that the most shittiest excuse to have them be assholes just cause.