Throughout the series, one of the telltale signs of someone being or containing a part of Xehanort is that they have pointed ears. Here is a gallery of each of them which shows their ears:
Master Xehanort
Terranort
Braig
Xigbar
Saix
Ansem (not as pointed as the others, but still a bit.)
Xemnas
This is every incarnation of Xehanort except one. And this one Xehanort brings up a question:
Young Xehanort. He is the only one (besides Ansem, arguably) with round ears. I think something must have happened to his heart that causes whatever body it occupies to have pointed ears. I think this could possibly be one of the plot points if this happens to him in KH3. Why do you think every other Xehanort has pointed ears, but he doesn't?

Master Xehanort

Terranort

Braig

Xigbar

Saix

Ansem (not as pointed as the others, but still a bit.)

Xemnas
This is every incarnation of Xehanort except one. And this one Xehanort brings up a question:

Young Xehanort. He is the only one (besides Ansem, arguably) with round ears. I think something must have happened to his heart that causes whatever body it occupies to have pointed ears. I think this could possibly be one of the plot points if this happens to him in KH3. Why do you think every other Xehanort has pointed ears, but he doesn't?