Best: Green, a.k.a GARY MOTHER****ING OAK. Good grief, what a delightful a-hole he was. You know all those Gary memes running about? They're 100% true. This scum bucket was everywhere, and every time you just wanted to step all over his inflated ego a little. But it wasn't until the very end that he actually admitted defeat. Ah, sweet satisfaction.
2nd: Silver. This is Gary with extra scum. This mofo is an all-out delinquent, and he did a great job at being the first rival I wanted to strangle. This is why he's second and not Barry--because he actually made me hate him. He stole his starter? Whatever. Hates Team Rocket? Whatever. But it's the fact that he appears so often just to try and convince himself that he's better than me that gets under my skin.
3rd: Barry. This guy, like Gary, was everywhere. Only that instead of making it seem like he wins every time, he keeps thinking that he has a chance to beat me--and even though he's somewhat of a pushover, I respect him. Level 85 starter? Yeah. And the fact that he healed my ignorant arse in the Spear Pillar was also awful nice of him without being too sweet.
Worst: Brendan. This little **** was a damn pushover. His pokemon were weak, he gave up halfway through, and had no use other than reminding us of his pitiful existence. It's a shame too, because he's the best looking male character IMO. He wasn't even a rival. Now Wally was a rival, but he was also extremely buddy-buddy with you. He's like Barry plus the much-needed Prozac, which leaves us with blandness. His team was adorable (seriously--Altaria, Gardevoir, Delcatty, Roselia...lulz) but I would have liked it if he appeared more.