The cast of Dragon Drive, featuring hero Oozora Reiji and his dragon Chibisuke in the center
Dragon Drive is about a boy named Oozora Reiji, and his adventures in a virtual world. No, not The Matrix, this world is where children go in secret away from the adults, to play a game called Dragon Drive. Each child gets his or her own dragon, hand picked by his or her own personality. Reiji goes to check this place out and finds himself with the weakest dragon there: a tiny squirt, which he names Chibisuke. But what he didn't know was that inside Chibi was a power stronger than he thought.
The manga and anime provide examples of:
The Ace: Anime-only Tachibana Kyoji is seen as this at school. Subverted in that he is soundly thrashed within seconds by Himuro at Dragon Drive.
Anti-Hero: Himuro Hikaru and Sumishiba Ichiro after parting ways with Toki. Both go down a level (Himuro from V to IV, Sumishiba from IV to III), but Sumishiba is more mentally balanced to begin with, and Himuro remains a much darker character.
Ash Face: Each episode of the anime features an eyecatch where Chibi blasts Reiji with a burst of flames.
Ax-Crazy: Himuro in the anime and first half of the manga.
Badass: Himuro Hikaru, especially in the second half of the manga. Sumishiba definitely has a few scenes of his own.
Silver. Former dragon-buster and a Dual Wielding master. She probably beats Hikaru for Badassery in part 1.
The Berserker: Rokkaku, generally when he's had a little too much to drink.
Big Damn Heroes: Reiji, Maiko, Hagiwara, Towa and Tachibana in the final battle in the anime. Also, Himuro does this twice. Once when Reiji is about to get eaten by a dragon, and Hikaru shows up on his new dragon and fries it; and another time in the anime when Reiji is fighting and losing against one of the Shishinryu.
Bittersweet Ending: They defeat the Big Bad, but only by merging the two worlds, which causes the dragons to disappear. However, we do see that Future!Takumi revives Dragon Drive 17 years later, so they get to see the dragons again.
Brilliant, but Lazy: Otohime Taro, from the second half of the manga. Will fall asleep if nothing "interesting" is happening, and won't fight unless he thinks it will be exciting. He is also the best Dragon Drive player around.
Himuro might also count, in the beginning. He's a high school dropout because he simply got bored with it, and only rarely shows up at the Dragon Drive center to kick the asses of everyone in the place before going home.
Broken Ace: Himuro. Originally seen as perfect and the unmatched champion of Dragon Drive, he loses it when Reiji manages to catch him off-guard and nearly defeats him. Clearly has a serious inferiority complex, and actually breaks down into Manly Tears at one point when Reiji refuses to fight him.
Death Glare: Himuro has a very effective one. Somehow, he even manages to pull one off without opening his eyes after the Time Skip.
Disability Superpower: Subverted with Himuro after the Time Skip; his eyes are always closed, not because he can't see (presumably), but because he stopped using his eyes in order to sharpen his other senses and gain power.
Lightning Bruiser: Chibi in giant-awesome-beast-mode on occasion, both of Himuro's dragons, Shinsaber in the anime
Loners Are Freaks: Himuro. In the anime, he even has a speech about it. He literally does not understand the concept of friends, and wants to figure out what the difference is between Reiji and him by fighting.
Even more so after the time skip, when he has been alone in Ri-Kyuu for ten years. Reiji tells the others that Hikaru has spent too much time there and will be useless to them.
Made of Iron: Reiji is the most prominent, but many characters suffer through injuries, explosions, and fights without the bat of an eye.
Magikarp Power: Chibi seems utterly useless until, out of nowhere, he transforms into a monstrous dragon.