When both Batman and The Joker were no longer young and needed someone to carry on their mantle, and it was, they both found a fit. One of the successors perfectly inherited the Joker's will under its own superior conditions, and the other found someone who seemed to be no less than Batman. But this does not hinder his success. It is true that he is not Batman, and he does not have the style that Batman should have, but it is he who makes Batman's existence more valuable, and he has advantages that Batman does not have. Never doubt yourself, don't live in the shadow of the success of your predecessors, you don't need to be the second so-and-so, but to be the first yourself, and to live out your own value.
View more about Batman Beyond: Return of the Joker reviews