Luffy doesn’t like teach thing he likes learn from other characters how they fight. To adapt his fighting style
Zoro-has his own self improvement to work on
Sanji- know ovey-dovey personality I don’t think he would want train the female characters. He would food boast their stamina and recover Their energy.
Jinbei- is martial artist sure he could help them and guide
Yamato-is well train character herself. Especially the weapon she wheeled you have to be well trained in order utilize his weapon for war. Knowing big battle lie ahead. That can come out direction I think she would be helpful in that.