Fleshed out endgame characters.
Look at this photo. Out of all these characters only Luffy, Koby, and Buggy are fleshed out characters, while we still have a lot to learn about Garling, Imu, Sabo, Shanks, Dragon, the shadow, and Blackbeard. We know a decent amount about Akainu and Aokoji, but I feel even then we still need a little more from them to be fleshed out characters. I'm not asking for detailed biographies about each of them that explain everything about them, I just want to learn a little more about the characters that will be important in the final saga.