Master Splinter has yet to reveal what it is Michelangelo must improve on, other than a need to focus. In the First Nickelodeon TMNT Comic Master Splinter states that Mikey has more raw talent than his three brothers combined. Later in an episode, he says that Mikey has his "challenges" too. And even if Mikey can give his brothers grief, they will always care and love him and have his back. It is heavily implied that this version of Michelangelo has some form of ADHD.