I also wanted to mention, now that I'm replaying Black, that Gen V probably has the best overall set of gym leaders to date due to them all having a role in the story. They're actual fleshed out characters, more in line with the manga interpretations than any of the games or anime, really, making me actually remember every single one of them on more than just design and Pokemon (though Lenora's Watchog is certainly a memorable little headache). By contrast, I can't even remember the names of the Gen VI leaders, or what half of them look like! Here's hoping Gen VII goes back to more interesting characters for leaders.