Arakune's Theme, Thin RED Line. It really captures just how insane and twisted he is, combining metal with disjointed piano pieces, violins that switch between shreiking and weeping, synthesisers and, oddly enough, flutes.
Thin RED Line II. Now with organs and guitar riffs that sound like something by Motoi Sakuraba.
Bang's Theme, REPPUU (Gale), is the perfect theme song for manly hero of love and justice.
And the vocal version, REPPUU ~Second Wind~, based off a vid from Nico Nico Douga. WARNING: This song is so manly, it's been known to make women pregnant. Exercise extreme caution!
Just when you got it couldn't get any manlier, the Live version was released. Bang's seiyu nearly lost his voice singing it, but pressed onward for great justice and finished it. MANLY.
Endless Despair, Unlimited Hazama's theme. A theme that conveys, quite perfectly, the message that you are now fighting the very evil main villain, he is using his true power, and he is going to kick your ass.
Endless Despair II, which is now doubles as both Unlimited Hazama's and Terumi's theme song. Even without the horrific imposing intro, this is a song still fit for a madman who wants you outright dead at any cost.
The console version gives us a new character: μ-12. She's the True Final Boss of Story Mode, so she has to have an epic theme, right? And she does: Sword of Doom. A theme with lyrics describing a sword of sin, stained with blood and death, falling into the azure.
And if you thought the song couldn't be made even more awesome, here comes Sword of Doom II, which ditches the ominous chanting of the original and instead sounds more heroic. "Sword of Salvation" jokes abound.
Alexandrite, Makoto's theme, is very fitting: spunky, upbeat, and leaves a very big impact indeed.
Here's Butterfly Sky, the vocal version of Alexandrite. Becomes a heartwarmer if you know what the lyrics mean. Check out Makoto's entry under BlazBlue for more info.
Butterfly Sky II, a remastered version of the original with re-recorded lyrics from Tomomi Isomura.
Alexandrite II with a new music box-style opening that slowly builds into the classic active squirrel girl theme we all know.
Plastic Night, Relius' theme. It gives a boss-like feel while sounding evil and gentlemanly at the same time. Not only that, it has one of the most sweet sounding riffs in the series. They're seriously beautiful.
BUSIN, Amane's theme. The use of Japanese instruments definitely gives it a classic feel. But don't let the soothing intro fool you, when the guitar riffs start to kick in, you'll realize that Amane means business.
Fatal Judge, the Arcade Boss theme. Just right for the ultimate culmination of any given character's arcade story. In the story, this is used as the theme for Kagura vs. Azrael.
THE HIGHLANDER, which plays during the battle against Take-Mikazuchi and works wonders for telling you that you're up against a gigantic, horrific monstrosity, the very same one that obliterated Ibukido and Kagutsuchi back when time loops were still a thing, and let's you know that this will be hell.
Under Heaven Destruction II, which adds a larger sense of duality to the song when you imagine Ragna represented by the chaotic, pounding guitar, and Jin represented by the elegant, yet crazed violin. And to top it all off, the ending has been regarded as so beautiful it has actually moved people to tears.
Black & White, the new theme song for Ragna VS. Hakumen matches. While the theme probably should have been around since the first game, it's better late than never and a true testament to theme of Order Versus Chaos in the series.
Sector7, the theme song for matches among members (Kokonoe, Tager, Makoto, Azrael) of said organisation. Befitting of a mysterious organisation. With a mix of techno beats to reflect their technological superiority.
Dissonance, the badass theme song for Valkenhayn VS. Relius matches.
For the console version's opening? Ao -iconoclast- by KOTOKO. As expected, kick ass it does.
Crazily enough, it kicks about as much if not more when it teams up with the Quad CityDJs. And thanks to League of Legends, this may well be the most famous version, and most famous song, from the entire game. Lots of people who otherwise know nothing about BB will recognize this song instantly as "Master Yi's dunking theme".