[RedMattis]

Instead of ultra-high base-stats the actual gameplay usually works out better if you buy them a bunch of advantages related to whatever their 'thing' is. For Batman you might want to build some of his gadgets as advantages f.ex. And give him lots of "Gizmo" so the player can pull out kryptonite, bat-fish-repellent or whatever he needs that fits his 'theme'.

And consider using either "Luck" or some sort of Fate-point system if you don't want Batman to randomly get shot from the back and die.

Generally 'rule of cool' or 'rule of drama' is the most important thing in that type of setting. If you want to nail the Marvel-feel anyway. Let's-build-someone-with-Batman's-stated-abilities is of course also a legit approach if you don't care for the Marvel-movie feeling.