Yes, to become the best fighter you can be, you need as much strength as you can get, and you don't get as much from bodyweight wxercises. Focus on bench, squat, deadlift, clean and jerk, and snatch. Do some weighted situps for the core if you want. A few good assistance exercises are stiff leg deadlifts, good mornings, bent over rows, overhead press, power cleans, push press, and overhead squat. That should be enough to keep you busy. Shoot for 3x3 or 5x5 for your exercises. Use the biggest poundage you can handle for your reps. Just focus on the big three and the olympic lifts for a solid year and you will be MUCH stronger than you are now. For example, I have been powerlifting for about 9 consistant months, and it looks like at the 1 year mark, I will have added an average 100 pounds per lift for the big three.