What if he played a version of the Riddler that we only get to see through computer and phone screens, never in person, and Eminem is allowed to lean into Slim Shady a bit, with a few swears and a more aggressive performance. It would work better with him that way instead of, for example, a version of the Riddler from the Batman.
It’d be better then a silted performance throughout the entire thing. Plus, Eminem comes up with really clever rhymes already, so seeing riddles that he works with a team of writers would be great.
If anything Cory Michael Smith should come back to the role. He actually gave the Riddler depth. He wasn’t just some smart cocky genius who thought he was better than everyone else, he actually had a dark voice within him that drove him crazy, and he had charisma.