Don't even worry about weights. Muscles are not what it's about with BJJ, as you see when people are rolling at the end of class and skinny little guys are schooling the big hulks. Yoga, stretching and cardio for sure, because your flexibility and your conditioning are key.
If I was going to recommend any kind of strengthening exercise, I'd say just standard bodyweight squats, and lots of them. I found starting BJJ really killed my quads, so the squats will get them prepared for that.
__________________
|