Fighting
Robin's Best Skill Is One Batman Could Never Teach Him
While Batman is the best mentor a young crimefighter could ask for, it would be a lie to say he taught the Robins everything they know. He couldn't have built any further on Dick Grayson's acrobatic prowess and it'd be difficult for Bruce to top Damian's training with the League of Assassins. Jason Todd also has a superior street sense to anyone in the Bat-family and crosses the line where Batman cannot. As for Tim Drake, his greatest asset is a skill he developed all on his own.