A combination of the first 3 poll options, but I voted for "it came naturally." Like KM said, fighting is a natural instinct in lions, and even as small cubs they are practicing fighting moves they’ll use as adults.
Simba had learned pouncing/stalking from Mufasa, but it was the Nala-Flip that gave him the victory against Scar.
Simba definatly learned a lot before he was exiled, and I’m sure Timon and Pumbaa taught him nothing of fighting. So I think he built on what he had already learned while staying in the jungle.
During the fight with Scar, I think it came naturally, through pure instinct. Simba, being a lion, instinctivly knew how to fight, and with a little help from a certain move he picked up from Nala, he won.

I think Simba was going off pure hatred towards Scar by that point in the movie and after seeing his mother being abused, knowing that Scar killed his father and having his own uncle being on the brink of killing him, that would trigger his natural defense mechognisms as a lion. ^^ Same would probably go for any creature actually, but yeah, that's just my two cents. 







I'm kidding 
