I don't think she's the most intelligent, but I think she'd be the most serious about school and she'd study more than any of the other ones. She's also very knowledgeable and good at learning and understanding new concepts. After her, I'd say Rapunzel.

^Yeah, I agree. I'd pick Belle, Rapunzel, and Mulan when it comes to strength and improvement since they really show their best potential, but smartness adds some points for Mulan.

or Tiana.

And Mulan.