If the Slitheren and Gryffindor fought , which side do あなた think would be successful?

Probably Gyffindor but it depends on who is in the houses at that time :)

It's hard to say. I would say Slytherin, only because most don't play fair when it comes to competing, but on the other hand some are really cowardly and end up just running. It just really depends. Both houses have a strong pride personality.

SLLYTHERINE!

GRYFFINDOR

Slitheren, of course!

actually there really can't be answer if あなた were to just do duels between slytherin and grffindor because it all depends on magic skill and since we went based on harry's magic skill we dont know about everyone else so that answer would be completely opinionated

Slytherin, because we'd cheat. ;)

Neither. Hufflepuff and Ravenclaw win.
Cause after the Slytherrunners and Gryffindorks kill each other off becasue they are both to proud to reconcile their differences, we rule the school. ( I am kidding, btw, please don't take offense.)
Just saying. XD

Slytherin. Most of them like to use the dark arts.