World's richest AND smartest man, world's greatest detective and martial artist, who is instant master in any skill he needs and literally can and does bully godlike beings, because everyone is afraid of him, has 100% succesful method to kill any powerful being on the planet at will, armor capable of curbstomping gods, a robot who can instantly copy anyone's speciality or powers and become their superior in every way, walked out a broken spine and no-sold being laser-point nuked in the face by cosmic god of fascism and has supergod of evil ensuring he always wins as cosmic constant and if he dies he is reborn as Batman in another universe. Batman is far more removed from regular human than rest of Justice League combined.
The thing Tulok noticed is that it is very hard to do a "Z Fighter" build in 5e because it requires a character who
- Can fly
- Has any form of ranged energy attack
- fights unarmed while having high physical strength
- doesn't wear armor
Each of these things requires different things in D&D and the character becomes mediocre at everything by grabbing them all, isntead of focusing in one place. That being said, you can look at his Frieza and Trunks buils, which eschew just one of these four traits each (Frieza wears armro and Trunks uses a sword).
Again, the issue is that Batman is just best in the multiverse at anything and everything, in his new series Tulok
did dwelve into how a correct way to build him is to zero on an aspect you like and work on that.