Every time you train in your career, you'll pick a category to improve and spar with. This is done during training camp.
Each time you do this, you'll have anywhere from 1-3 optional challenges to complete, which reward you with evolution points and XP for moves.
Simply complete all of the challenges it gives you in a sparring session until no more pop up, and the achievement will pop once back in the menu.
Please feel free to message or comment with any questions. Happy hunting!