Unofficial sort-of follow up to an earlier post. Really just because I feel like. So there.
Note that this is based off a combination of character histories, artist renditions and gut feeling. Feel free to disagree. (But knowing all three of you guys, I doubt you'll really care...)
Bruce/Batman: He's not a natural prodigy in the martial arts, he worked himself to the peak of human ability and he stays there through constant training. So he's built, man. He's got muscles living on muscles and he's keeping them, because he CAN. He's probably a bit top-heavy (lots of guys who work out a lot are) especially because of the constant rooftop-leaping, which is harder on the arms. He runs, sure, but if it's too far for the decel lines, he probably uses the batmobile, meaning that his legs simply aren't getting the same unintentional workout. His fighting style favors a more straightforward approach - punch, kick, etc. Not a lot of flipping and such unless necessary, so he's more grounded a lot of the time, and can afford the bulk.
Dick/Robin I/Nightwing: Definitely lighter than Batman. He had the acrobatic skills in the blood, it comes much more naturally to him, so he's not as focused on the constant weight-lifting a la Bruce. This isn't to say Dick lets himself get out of shape, but he's going to be skinnier, less ripped. His style depends a lot on being able to flip, spin, and
move whenever and wherever he wants. I imagine that his training focuses a lot more on the karate/martial arts type of practice. He uses his legs a lot more then Bruce, to propel him around everywhere, so he has a more balanced build. Also, his style lends itself less to the punch-kick-while-standing, so he ends up in a crouch or a flip more often then not. (I must note somewhere: this all must be KILLER on his knees. Seriously)
Jason/Robin II/Red Hood/ Red Robin/Nighting II/?: He must have had some natural ability, or he frankly wouldn't have made it as long as he did. Possibly he's got more even then Dick, because Dick's been in some sort of training since he was a kid. On the other hand, Jason grew up on the streets, which favors knife fighting (where you try to stay out of the other person's range and slash at them whenever possible) or skin rumbles, where you grab the other person and try to get them on the ground as quickly as possible. He's not going to have the straightforward training of Bruce or the natural flair of Dick. I think he'll favor Bruce in build - more heavy and muscled, especially as weight training is easy to pick up and do on your own. I think his style would also favor Bruce - more straightforward, at least at the beginning of a fight. He probably only had enough time to cover basic basic martial arts with Bruce, so nothing fancy, more straight punches and jabs. The moment where a fight gets out of hand, he'll play dirty, not doubt about it. I find the comics that depict him flipping around like Dick to be a little weird, he doesn't have the background for it, and I doubt Bruce would train him in that style.
Tim/Robin III/so far...: Tim also doesn't come by his skills naturally. In fact, I think it's largely overlooked these days that Tim favors brains way over brawn. And he was like that before Batman, people. Tim's a detective at heart. But Tim does value the physical aspect of the job (and he probably gets a huge thrill out of it as well) so he's probably trained his butt off to get good at it. In face, his training was more intense then Dick's or Jason's (and definitely more intense then Stephanie's two weeks.) because he no only globe-trotted for it, he also trained with SHIVA. She's bad-ass, and she'd be much harder on him than Bruce ever could, 'cause she's EVIL. Build-wise, though, I just can't escape the image of a scrawny teen with wiry musculature. I just don't think Tim could put on the muscles the way Bruce does, at least not at his age. Tim's pretty built for his age (lucky him the "loose and layered" look is in for guys, so he can hide it better) but he's not sporting football player arms or anything. His fighting style will be REALLY straightforward, as he's probably taking all his moves right out of the books he pores over in his spare time. He might mix 'n match styles, but no spontaneous flipping from this bird.
Barbara/Bagirl/Oracle: As it seems pretty canonical that she's been training for some sort of crime-fighting since she was younger, I imagine that she'd be working out pretty hard from an earlier age. Less formal training than Bruce or the Robins, she'd probably favor the more standard martial arts she managed to learn at city dojos (Karate, Tai Kwan Do, etc.) and she's gonna do a lot less flipping that Dick. (actually, we can all admit that EVERYONE does a lot less flipping that Dick. So there.) As she's also a brainy, like Tim, she probably does her stuff more by-the-book. She's gonna be lighter than the boys due to sheer genetics, but I'd imagine that she' d be pretty muscled for a girl. Also, she'd probably be pretty flat (sorry boys!) because it's hard to be a serious vigilante with DD cups. Now, as Oracle she's definitely more muscled in the arms/chest area as she basically can't exercise her legs. But I imagine she's got some serious arm muscles now, even more so that when she was Batgirl. Also, as Oracle, she can take you down from 20,000 miles away with her cell phone, so I wouldn't really mess with her anyway.
Cassandra Cain/Batgirl II: I imagine Cass having a build more similar to Tim - more wiry than thick, but I imagine Cass's muscles are pretty impressive for a girl, considering she's been training since she was born, essentially. I also think her moves would be much less formal than everyone else's, because they're not separated into categories in her mind the way they are for everyone else. Her first language is movement, and it all probably blends for her. She'll use the best move for the occasion and move seamlessly into a totally different style immediately, Obviously she can recognize the styles of others, but she doesn't think through her moves the way Tim probably does. I have a feeling Cass might be a little short for her age - shorter people tend to do better in acrobatics, and she's waaaay flat, due in part to the lifelong training regiment.
Stephanie/Spoiler/Robin IV: She actually had some gymnastic and martial arts training before she became Spoiler. Plus, she has some crazy natural sneaking skills, because she's snuck up on Tim a bunch of times. She's not as muscled as Cass, and given that she's a gymnast she's probably more well-balanced, even though she favors punching people. She probably leans the most towards Dick in style, (more crouching) due to the gymnastics, but she is nowhere near his level. I don't imagine her having the same sort of training regiment as ANYONE else (she seems to have a life, sometimes) but given that she's been told to quite multiple times and refused to give up, she clearly keeps herself in shape deliberately, despite her limited resources. Also pretty flat (GYMNAST!) and she's exactly average hight, apparently.
Helena/Huntress: I know the least about her, honestly. Given that she came into the crime-fighting older than anyone else, her style is probably more stiff and straightforward, less natural then those young whippersnapper sidekicks. She clearly has less restraint than the rest of the family, and I imagine her kind of barreling into fights, punching people out without much finesse. Probably tall for a woman, and I'm putting her as the most stacked of the Bat-women, just because it would fit with her. (remember: women can't crime fight with crazy cleavage. So she is AT MOST average. Nothing spectacular. Really!)
People I know too little about to do a real analysis:I know almost nothing about Azrael, so...nothing doing there.
Misfit is a scrawny pre-teen who doesn't do much hand-to-hand.
Alfred is an older guy in awesome shape, but he uses a shotgun whenever he has to fight, so I can't imagine him doing more than the old one-two in a fight. He's too awesomely British.
And Catwoman is very athletic and muscled, and incredibly informal in her style. She's just slinky, catlike. Well-balanced, not at all bulky and straightforward. The opposite of Batman, as it were.
Damien Wayne is an incredibly over-trained child. A bit like Cass, but I imagine him being far less fluid in his style.
I have no clue about Batwoman. Where did she come from, anyway?