Uzamaki Naruto
It's ironic that Shikamaru and Naruto are such good friends, because first of all the two were never ever friends to begin with (Naruto thought he was a big mouthed idiot), though they seemed to get in trouble together for not concentrating in class (But so was Chouji and Akamaru). But why ironic? Because Naruto is trying to prove to the world that hero's exist and he desperately wants to be one while Shikamaru is desperately trying to avoid any occasion where he could be viewed as a hero. Also, Naruto strives to be acknowledged and live the life of a famous person while Shikamaru strives for mediocrity. (Which explains why he wasn't very happy to be the only Genin from his class to become a chuunin.)

Uchiha Sasuke
Sasuke and him don't talk all that much. Probably because Shikamaru is busy being pushed around by Naruto. Shikamaru recognizes that in the circus of Ninja's he is merely a side act to Sasuke, if even that. Still, Shikamaru's smarter.

Haruno Sakura
Sakura can be really annoyed with Shikamaru's lack of urgency, and lack of duty to the village. She really doesn't know that he's smarter than her, but she does not that he can shake of mind spells just like she can (which most ninja's other than some Chuunin and the Jounin can do). On the whole she doesn't trust him because he's very good at running away. She also knows that he's not found of girls so she probably doesn't like that either.

Yomanako Ino
Shikamaru and Ino seem to share mutual annoyance with and occasional respect. (Of course, i think Shikamaru likes Ino. ^_^;; Forgive me if that's really wrong or blatantly obvious). The problem is is that Shikamaru seems to have a bit of a girl problem, as in he doesn't really like them very much, and he especially hates strong willed woman such as Ino and Tsunada. Probably because his mother is a strong willed woman so he thinks his father is well, pretty whipped. He also doesn't like how she always hurts Chouji's feelings.

Akimichi Chouji
It seems to be more pity on Shikamaru's part, but he generally likes Chouji. It's cute, their conversations. It always seems like they talk about mindless things, like girls, but in truth they are really analyzing each other. The both concede that they cannot compare themselves to each other (which is really Shikamaru really just being nice to him because he knows he's better), but never the less, Chouji really admires Shikamaru and says that he's better than Neji and even Sasuke. He also says that Shikamaru is smart and funny. Chouji is often caught in jealousy, but Shikamaru always says something that makes him feel better.

Sarutobi Asuma
Asuma seems to be paying to much attention to Shikamura these days, leaving poor Chouji feel neglected and lacking in the self confidence department and Ino is too busy about being thin and getting Sasuke to care. Asuma is very fond of Shikamura because he is the ultimate diamond in the rough (except for Naruto) because he thought Shikamura was a one jutsu failure. When it turned out he was a genius, Asuma paid him a great deal more of respect.

Hatake Kakashi
Kakashi is too busy paying attention to his own blooming prodigies to really pay attention to other students. He does, of course, but he just observes so his and Shikamaru's interactions are minimal. But it's obvious Kakashi knows that Shikamaru is strong enough (or smart) to know how to ward of a mind spell, and he knows that Shikamura is a born leader so he made him go on a A-Rank Mission to go after Sasuke and Gaara.