Possible Answers to some common questions
First about Batman surviving Darksied's pounding. Remember, he had a Mother Box with him, which is incredibly powerful in many ways, it's how he reprogrammed the hellspores in the first place. Along with the armor it shielded him from much of the damage, which was made more clear in the comic.
Second, Batman fighting in the Doomsday attack. Even if they were full powered copies of Doomsday, Which is what the probably thought at first, Batman's isolated on an island, surrounded by his fellow friends and warriors; a suicide fight to the death would be preferable to him then running to hide, leaving everyone else to slaughter, which would include Superman if all the Doomdsays were real. Notice the non powered amazons didn't hesitate either. Also, if you notice, before Batman attacked, several non powered amazons took some of them down, so Batman then knew he wouldn't be totally worthless.