Ultra Super Saiyan: Ultra Super Saiyan is well accomplished by most Super Saiyans, and is not necessarily between Super Saiyan 1 and Super Saiyan 2. Meaning that this transformation is more of a larger extent of Super Saiyan 1. When this transformation occurs the muscles grow massively, the golden aura also increases, and the depth in the golden-blonde hair is increased visibly. Due to the large muscles, it does increase your strength tremendously, though it slows you down terribly. Most Saiyans look at this transformation as a down side. All Saiyans that went Super Saiyan 2 went through this transformation first, except Gohan.
Super Saiyan 2: This transformation can only be achieved by extreme anger. Though not many saiyans achieve this, some say this is the most effective Saiyan Transformation. In this transformation the muscles grow a bit larger, the body size increases slightly, the hair turns just about pure gold, and its hair's depth is also very visible. The golden aura surrounds them, along with electricity crackeling around and within the aura. Usually when a Saiyan reaches Super Saiyan 2, there is one strand of hair hanging down on their forehead. Super Saiyan 2 has the same effects as Super Saiyan 1, except to a greater extent.
Oozaru: When a saiyan with a tail is exposed to the moon, it automatically transforms into a large monkey-ape beast. When a Saiyan is in this transformation his/her power level is multiplied by 10, giving it incredible power. The only ways to reverse this transformation, is to get rid of the Saiyan's tail, or get rid of the moon.
Golden Oozaru: Golden Oozaru is basically the same as regular Oozaru, except it is much more powerful and the Oozaru's fur is Gold. Some say this is the most powerful stage of a Saiyan, and to reach this, when a Saiyan with a tail that has the ability to go Super Saiyan is exposed to moonlight, then it becomes golden Oozaru. How it can be reversed remains the same way as how it can be reversed for regular Oozaru.
Super Saiyan 4:This is the final transformation a Saiyan can achieve. First a Saiyan must be exposed to the moon, and turn Golden Oozaru. Then the Saiyan, as Golden Oozaru, must be completely enraged, and put all of that anger into his/her power, to go beyond Golden Oozaru. If it is done, the Golden Oozaru will transform into Super Saiyan 4. This is the strongest transformation, and has no downsides.