Kid Buu is destroying planets throughout the universe. He learned instant transmission and has crossed over into the DCU.
Martian Manhunter is the only one at watch towaer who picked up the havoc, and rushes off at lightspeed to earth, only to find Kid Buu stating at the tip of the Empire State building, ready to attack. knowing this city has suffered enough Martian Manhunter interviens, by slamming his fist into Kid Buu's face sending him crash landing into the Rocky mountains of Denver Colorado.
Kid Buu's quick recovery helped him meet Martain Manhunter over Lake Michigan, where a battle to the death bettween two Godlike beings begins!
Character morals apply.
No BFR fight is to the death.
PLEASE LEAVE OUT THE FANBOYISM! And give valid reasons as to who wins this fight and why. neither can simply one shot the other.