before bruce banner became a hulk the master hulks were fully awake but then the slept for one million years long. since the abomination attack on the hulk a.k.a. bruce banner, they were awakened beginning with the legendary dragonhulk, then demonhulk, hydrohulk, heat-she-hulk, infinityhulk, bronzehulk, and so on and so on.
dragonhulk is the #2 on ultimate power and size, while demonhulk is #1 on it. the master hulks were long thought to be dead , but, they still live. now the evil hulks from the hulk's past have come back to life. devilhulk, redhulk, all of them. with the evil master hulks the nearly destroyed half the planet.