Yamamoto is the type of character that can make friends with everyone, and if not friendship, then at least respect. Characters like Hibari, have been shown to have interest in Yamamoto's battles, and Squalo has also shown to have interest in his development to the point of willingly tutoring him. However, Yamamoto can become angry when his friends are hurt or injured. He is also willing to sacrifice things important to him to save his friends from danger, as shown in the Kokuyo Arc. where he sacrificed an arm (right before an important baseball game) to defeat Ken; and when Squalo asked him whether he would choose baseball or the sword, he chose the sword in order to protect those he cared about. 

In school his grades are around the same as Tsuna's because of his focus on baseball. However, it is shown that once he sits down and actually learns the theory, he can do any problem easily. Despite not being smart academically wise, he has shown an inner wisdom and tact belying his age. This was shown when he scolded Gokudera on being a proper right-hand man. He has the tendency to believe that everything is a game, including the Vongola which he believes to be some sort of 'mafia role-playing game'. His future self, however, seems to have finally acknowledged the reality of the situation. 

Voice range: Med, to high

Voice type: Crazy/excited, energetic

I think this accurately depicts the voice I'm looking for:

https://www.youtube.com/watch?v=F1bMCl123DY