I'm not sure why Gryffindor and Slytherin hate each other.
Or why no one is friends with each other, they just sort of mutually respect each other.  Honestly I think that:

~Gryffindor would be good friends with Hufflepuff and Slytherin.

Hufflepuff: Are you sure this is a good idea?
Gryffindor: Relax, it's fine. *ties harness* this is magic. Bungee jumping off the stairs with it should be perfectly safe.
Slytherin: *holding video camera* Oh just hurry up so I can get a video of you falling face first onto the floor.

~Slytherin and Ravenclaw would have sort of a frienemy thing.

Teacher: So what's the proper charm to open something?
Slytherin: *raises hand *
Ravenclaw: *waves hand*
Slytherin: *jumps up and down in their seat*
Ravenclaw: *waves hand frantically*
Slytherin: *tries to push Ravenclaw's hand down*
Teacher: Ravenclaw!
Ravenclaw: *smirks*
Slytherin: *huffs, rolls eyes* It would be you.

~Ravenclaw and Hufflepuff would kinda talk to each other:
Hufflepuff: Hey, did you get the homework?
Ravenclaw: Yeah. *shows sheat*
Hufflepuff: Thanks.

~Ravenclaw and Gryffindor would HATE each other:
Ravenclaw: That is so stupidly dangerous. There's at least a 70% chance of injury.
Gryffindor: Yeah well your face is stupid!

~Hufflepuff and Slytherin would just stay away from each other because Slytherin kinda scares Hufflepuff.
Gryffindor: Hey so do you guys want to hang out sometime?
Slytherin: I've got nothing else better to do.
Hufflepuff: O-Okay... *sits farthest away from Slytherin*