With Gen IV, Game Freak decided to take more risks with a few songs in the soundtrack. That gives Gen IV a bit of an edge over Gen III for me, because overall I don't think Gen IV is that much better, but the songs I like from it I really like.
Let's start with the
Opening, which starts off sounding mysterious before going into the standard Pokemon opening music. It's a good way to start these games given the kinds of lengendaries we meet in them.
Gen III's
Pokemart theme is back, and still good. Gotta go buy some Super Repels!
More
Wild Pokemon,
Trainers, and
Gyms. Again, they're okay. I like these a little more than Gen III's, but they're still nowhere near as memorable as Gen I and II's.
Rival battle. Eh, it's okay, but probably the weakest Rival battle in the series.
Encounter Team Galactic. This is pretty good, a great fit for some sleazy villains.
Team Galactic Building. Pokemon has never seen such a slimy bunch of thieves.
Team Galactic Grunt Battle, nice, the grunts in the evil team have a good battle theme again!
Team Galactic Commander Battle, fits in nicely with the previous Team Galactic themes.
Team Galactic Boss Battle, it's a different kind of song from the other Team Galactic themes, but it's not bad.
Uxie & Mesprit & Azelf Battle, not bad, it sounds powerful, but not in a way that's oppressive, it works for these legendaries.
The
Game Corner, the last time we'd be able to gamble in Pokemon(at least until the wondertrade, Wurmple :/, Wurmple :\, 6IV shiny Metagross?!), it's catchy and cheesy in all the right ways.
Mt. Coronet. Alright, one of my favorite area themes in the series. I've always been fond of snowy areas in video games, and this theme captures those kind of areas very well. This song has stood out to me from the moment I first reached it.
Spear Pillar, an ominous theme perfect for the the location where we fight a couple of gods.
Dialga and Palkia Battle. This is a big change from Spear Pillar's tone, instead of trying to make the player fear the power before them, it just sounds otherworldly. A great choice for the fight against those that control time and space.
Stark Mountain is perfect for exploring a volcano.
Platinum gives us the
Distortion World, an ambient track, something that doesn't happen often in the series, which helps make the trip into this strange world stand out all the more. Bonus points for the song leading into...
Giratina Battle. This song is all over the place, it's so strange, and I love it. I couldn't ask for a better theme for a creature that lives in a world so alien to humans.
And to end the main Gen IV games, it's time I talk about the best champion in the series.
Cynthia's encounter theme lets us know that we a standing before the strongest trainer in all of Sinnoh. This elegant piano theme has always stood out for me, it's so different from everything I'm used to in Pokemon, what could possibly follow?
Champion Cynthia's Battle Theme. I love this song. It's easily up there with Vs. Lance/Red as one of my favorite battle themes in the series.