Canon.
Here is my canon pimping post in which I implore you to app Gaou. Or Marco. Or any dinosaurs. Or any castmates. Period. You can read Eyeshield 21 here!
PLOT
Sena, who is often bullied, eventually masks as the ultra fast football player Eyeshield 21 and wants to go to the Christmas Bowl. In a nutshell. Basically. FOOTBALL. And a psycho guy with guns, a fatty, an old geezer kicker, brothers who aren't really related, the big sister that's not really a big sister, the hyper girl whose brother is a just as hyper idiot, the fatty's apprentice who speaks in a language only understood by strong men... This is Eyeshield 21. Even though it's set in modern day Japan, these high schools are simply crazy about football and they all want two things: to get to the Christmas Bowl and to find out who the father is the real Eyshield 21 is.
Basically everybody in the series is a delinquent because their an idiot or a thug or a mixture of the two. If they're not, then they're probably a female character, which has its own boundaries and limitations outside the realm of manliness balls.
HAKUSHUU DINOSAURS
The Hakushuu Dinosaurs are the unexpected finalists in the Kantou tournament. They basically have a meat, a pretty boy, a guy who drinks cola, the former ace who nobody really cares about but acts surprisingly a lot like Taki except more dramatic (it's possible!), and their ice cube cold queen machine. As a team, they're all about strength. Let's take a look at the characters now, shall we?
KISARAGI
Kisaragi is a minor character, so he only appears in the match of Hakushuu against Seibu (chapters 243~247), in a sauna (chapter 251), the match of Hakushuu against Deimon (chapters 252~273), and for a split second when he donates his catcher glove (chapter 279). Anyway, let's take a look at his awesome teammates who get more of the spotlight than him.
GAOU
Gaou Rikiya is the muscle of the Hakushuu Dinosaurs. He's super strong and cavemanlike and I'd be lying if I said I didn't love him to bits on pieces! Despite appearances, he is a high schooler. 8|;;;
Despite being all strength, he has high standards of morality when it comes to strength and being a man, and reasons quite well.
He's hardcore.
MARCO
Maruko "Marco" Reiji will break anybody necessary to win. His special speech pattern? "I'd say" at the end of every sentence. He's a pretty hard character to play because he's so complex, I'd say. Major kudos to you if you want to take on a challenge!
Yakuza? Maybe. He's definitely dangerous.
Yet he doesn't want to fight any really strong people directly...
And he drinks a lot of cola.
MARUKO
Team manager and the girl Marco wants to show the morning after or something. She's kinda like an ice queen, real awesome. I mean. Look at what she's pulling here.