User blog comment:Captain James Rogers/Justice League V.S. The Avengers/@comment-34520466-20180130015016/@comment-11836-20180130020654

A few problems with this.

1) The Marvel universe doesn't have Kryptonite, so how would Tony know that a green rock would hurt Superman?

2) The Justice League still has Wonder Woman... and Batman... and the Flash... and a whole lot of powerful superheroes.