Batman from the DC universe is one of their prime characters and is built up with incredible detailing. His aspects, fights, moral code, neverending selfconflict, etc. are all shown in comics or animated series. His war on injustice and his morality of not killing them create much depth about the characters' choice of path. Batman is not an alien and neither is he gifted with any superhuman abilities. His willpower, intellect, and strategy have always brought him victory in most cases. His mental and physical conditions are at the prime and probably the best version any human can achieve. This makes him equal to all metahumans or superhumans.
In the animated series “Dark Knight Returns” we see how he beats down superman to a pulp. His skills can be best judged when he dodges Darkseid’s omega beams which is an impossible feat. Flash did manage to outrun once but Superman failed. Batman did not run or fly but just managed to bounce off a parademon confusing the ray’s direction to kill the parademon. He is rich and owns a wide gallery of weapons and armors that also help him in his battles. With all that said about the character, the question that follows is “What if Batman was evil” and that is not a very vague question.

0:00 Intro
2:33 Dark Origin Of Owlman?
5:09 Owlman Story In Justice League: Crisis On Two Earths
8:18 What Makes Owlman So Dangerous?
11:20 Evil Versions Of Owlman In Various Forms Of Media