*power cleans for explosive hips which I'm good at
*deadlifts for slamming picking up people in their guard
*closer gripped bench for pushing off
*heavy sit ups and ab exercises-> knockout power, connects top of body to lower body, overall dexterity in BJJ
I would say bench and squat, and whatever else you wanted to add. The movements don't apply to a lot of the movements in BJJ, but these two lifts are a pretty decent measure of overall strength since they are core lifts, which work a lot of different muscles. I dont have any real proof or anything to back this up, other than what I've seen at the gym. The guys that come in there benching 340 and squatting 450-500, are a lot harder to tap than the new guys that come in benching 180. They also get better quicker than somebody who isn't as strong.
Stick to heavy compound motions. Bench, squat and deadlift variants as well as military press, good mornings, rows and pullups are pretty much all you really need to be doing. I'm not sure how I feel about olympic lifting yet, largely because I really haven't done that much of it, but if you have adequate instruction, I doubt they could hurt all that much. For grappling, grip work and ab work go a long way. I do sledgehammer levering excercises, plate pinches and towel pullups for my grip, and I've been doing alot of hanging leg raises and saxon side bends for my abs. Neck bridges are great too, but don't do them unless you can get someone to show you how first. It's kind of hard to pull off a triangle choke in a wheelchair.
Alot of people have alot of opinions with regards to set and rep ranges. I stick to heavier weights and lower reps. The most important thing to remember is to make the bar move as fast as you can without sacrificing form. If you are training to increase your explosiveness and power, you really don't need to be worrying about time under tension. Any excercise that can be done standing should be done standing. Leave the machines for the metrosexuals.
From what I'm learning, it seems that BJJ uses "pull" motions much more than "push." I do a push/pull split for balance. But it seems like an emphasis on pulling exercises (deadlifts, rows, curls, etc.) would be good for BJJ.
I love this excercise I found where you go into pushup postion on two dumbbells. Instead of doing pushup what you do is pick up one of the wieghts to your hip and set it down and then the other arm. Its great for core, stabalizing and aggressive pulling motions.
Another cool one not really wieghts is to do pushups from straps hanging from a bar overhead. I look for some links.
the bodyweight exercises are infinitely more useful for bjj and grappling. get down into the hard bodyweight and gymnastic movements like one arm pushups, one leg squats, several different kinds of pullups, planche pushups, hanging core work (levers) and it will take you far.
im not saying that lifting doesnt have its place in grappling cause it definately does. the o-lifts are incredible for mma. cleans, overhead squats, push presses etc would all be good
These guys have given you some excellent suggestions already. I would concentrate on explosive movements with 50% of your max going as fast as you can. Lifting like a bodybuilder (ex. lowering the weight for 4 seconds, lifting for 2 seconds) will only slow you down. You should also concentrate on your core, putting in a lot of twisting motions to build explosive striking power. Stick to free weights because they work the necessary stabilizer muscles. Good luck man.