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I'd argue Silver is a better and more enjoyable rival than Blue since he has a more developed backstory ( being Giovanni's son but disliking Team Rocket for being bungling morons ) AND butter character development, from being a social Darwinist who despises weakness and treats his Pokémon like shit to realizing he needs to actually care about his mons if he want to win.
His Golbat evolving into a Crobat is probably the most subtle example of character development in the series.