Is it true that bulky people can't be fast like Bruce Lee or flexible like "Superfoot" Wallace or tall like the great Khalil? I want to be big, fast, and able to fight all at the same time.
Have you ever watched American football, or heavyweight Olympic lifting? What about the heavyweight and light-heavyweight divisions of the UFC? It's absolutely possible to be simultaneously big, strong, fast, and flexible.
The key elements are getting big and strong, then incorporating a lot of power training into your strength and conditioning program, and maintaining that weight while working on mobility and explosiveness.
YES, so much yes!
I have seen big bulky people contend in races. I have also seen bulky people out-spar their skinnier opponents in a dojo. It is possible
The above answers your question but I would go on a bit, if I may.
To achieve this,
p.s: A little informal physics... velocity is caused by acceleration which is caused by jerk which in turn is caused by snap <— this is what you want to decrease. I should add, "it ain't easy". You mentioned Bruce Lee who, in my books, was the master of minimal snap time. His acceleration posed a problem for video cameras of his time. Try to beat yours.
Sure, you can be big and fast. That said, there's some important ideas to keep in mind about what your training is going to look like. There's basically going to be 4 factors you are training (as far as conditioning) - power, speed, endurance, and, size.
To quote Wikipedia on Bodybuilding:
Right here you can see power and size are trained for differently. Then there's the issue of endurance (which varies on how you expect to use your martial arts and in what conditions).
Finally, speed. The usual adage of the slow bulky guy isn't a matter of too much muscle as much as result of bad training.
Here's where we go into neuromuscular science... your body has a natural reflex reaction when a part of your body is moved too fast - it tightens the muscles around the joint to serve as a braking action to stop the joint from getting injured. The extreme result of this is a muscle pull or muscle tear - the body decides to let a muscle take damage rather than a joint because muscle heals easier.
When it comes to resistance training, the advice to stretch after a workout is so that you can reset your muscle spindles back to normal full ranges - otherwise they will set their "default" at a shorter range - and when you try to move fast, your own muscles serve as a braking factor to your speed.
So it's not that more muscle slows you down, it's that muscle training that ALSO sets the muscle spindles to a smaller range of motion, done over long periods of time, slows you down. Stretching after resistance training isn't about getting more range of motion, it's about keeping what you have and making sure it's available when you move at speed. Reset the muscle spindles and you can keep your fast movement.
Beyond that, then it's really about developing your flow and ability to read the movements of an opponent in martial arts. There's plenty of folks who aren't fast, if you watch them, but when you're facing them they're a step ahead and sometimes you can't track their movements well - because they've figured out how to read you and not telegraph their own movements in return.
Yes you can. But in general you need to train your muscles in a balanced way so that you don't overdo one and thus de-emphasize the others.
There are different types of muscles in the body. There are muscles for strength, power and speed, the latter is generally known as fast twitch muscles.
Those that are bulky in a muscular way, such as a very large body builder, tend to be slower because they've over emphasized one type of muscle over another. But of course it all depends on how bulky you are talking about.
Van Damme is a pretty muscular guy and also quite fast. My second Master was a very big guy and was faster even than Bruce Lee while his arms and muscles were over twice the size of Bruce and he was over six feet tall and come in at 280-300lbs.
So you can do it but you have to do some research and become educated on different types of working out and exercises for different effects and maintain a balance otherwise one type of muscle fiber will suffer over the others.
One would need a picture to see exactly what you mean by bulky.
You can however reach an optimum where you develop the maximum strength in the minimum volume (lean muscles) that allows you to be fast and flexible enough. Martial arts isn't about force, as in brute explosive force, as you don't try to lift your opponent over your head or snap his bones in two. Excluding the actual fighting techniques, a fighter needs to have stamina (lean muscles) to keep up a long fight, speed to attack before being seen and flexibility to execute extreme movements without injuries.