I mean, Obito could probably kill Batman with barely any effort, but it would make the situation way more complicated and Obito has no reason to kill Batman. Not to mention that Obito is hiding most of his abilities as a shinobi, so Batman's plans will fail.

I mean, Obito is restricting himself to minimal levels of strength because he doesn't want to reveal his cards. Obviously, Obito at normal strength could stomp all over Batman. As for Batman's skills, the dude had literally mastered over a hundred martial arts, don't underestimate his ability to fight. Meanwhile, there are barely any shinobi who focus on pure Taijustsu, except for Gai and a few other exceptions.