Hi Emily. Following are my opinions on your question. Others may differ.
Black and White has an ensemble cast. Robert is in and out of the movie quite a lot. Some violence. You won't want to miss his scene with Mike Tyson.
Eros has three short stories - Robert is in the one called Equilibrium. Very esoteric. One of my favorite of his performances. Low key. No violence.
Game 6 - Robert is in and out, but the last 20 minutes are worth the whole film for RDJ fans. He's remarkable in this role throughout. Sure, a bit of violence, but it's rather comical.
Natural Born Killers - extremely violent, Robert is featured and the climax is not pretty.