Broly Character Facts

Broly is a light-skinned Saiyan with dark eyes and long black spiky black hair reaching mid-back with short bangs framing his forehead, rather like Gohan's hair in the Saiyan Saga. As an adult Broly is very tall with a lean but well-built frame. He wears a crown with a blue jewel that his father uses to restrain him from transforming into the Legendary Super Saiyan. In addition to the crown, Broly wears a golden necklace, boots, wristbands, and a belt that all sport blue jewels like his crown, along with golden bands on his upper arms and neck that later break off upon transforming into a Legendary Super Saiyan. The rest of his attire consists of white pants and a red sash similar to the one worn by Kibito. 
As a Super Saiyan while wearing the crown, Broly's hair takes on a neon blue color with a purple tint and appears fully purple in dark environments. As a Super Saiyan without the crown, his hair takes on the signature golden color of the form. As a Legendary Super Saiyan, Broly's hair retains the golden color from his Super Saiyan form while gaining a faint green tint. In addition to this, Broly's muscles become engorged to extreme levels and he also grows taller by a few feet after ascending to this form. 
Broly's personality is similar to that of a psychopath as he generally exhibits tremendously uncontrollable rage and is uplifted by the very idea of bringing destruction and inevitably crushing his enemies. He loves nothing more than to destroy things, as shown by his wanton destruction of planets for little more than intimidation; his bloodlust is such that Paragus once described Broly's actions as being destructive even by Saiyan standards. Broly also has a tendency to toy with his victims (as evidenced by his statements, such as "If you'd just let me kill you all before, you wouldn't be dealing with this pain now.") and enjoys playing with his feeble foes with sadistic sarcasm, often teasing his opponents with a plethora of 'free punches'; Broly himself rarely has anything to fear from any opponent he faces, which may have contributed to his arrogance. It is implied that Broly might have grown insane from living with the pain and fear endured by he and his father for so long; he has a tendency to become hysterical, laughing abruptly and maniacally (as seen during Paragus' flashbacks to his youth and his first being adorned with the crown), and even kills his own father ruthlessly for trying to abandon him. However, Broly's most defining trait is his hatred for Goku since infancy; this due to infant Goku's crying greatly irritating Broly, which would lead him to carry a subconscious hatred of Goku for the rest of his life. 
Broly was born in Age 737, during the period of intense turmoil between Frieza and the Saiyans. At birth, his most curious feature was his inordinate power level of 10,000. This anomaly meant that by birth, Broly's power had already been close to that of Bardock and King Vegeta at the time of their deaths (which coincidentally happens during the afternoon of Broly's birth). In the Saiyan delivery room where he rests afterward, Broly is grieved by the constant disruption of his literal 'crybaby' neighbor, Kakarot (later rechristened Goku). These neighboring babies are the butt of a joke by presiding doctors, who rave over Broly's power level but criticize his reaction to Kakarot's crying, while also criticizing Kakarot's then-measly power level of 2 while also stating that though he has a low power level, he has the spirit of a Saiyan. Kakarot's crying affected Broly's psychological state of mind, causing him to hold a subconscious grudge against him. The two infants would not meet again for almost three decades. Born with supernatural power, Broly awakens as a Super Saiyan at a very young age.[4] Broly's exceptional gifts branded him as the first Legendary Super Saiyan in approximately 1000 years. 
During Broly's first psychotic outburst wherein he pursues Goku, he transforms into a Super Saiyan, although his appearance in the form differs as a result of his crown restraining him from transforming into his more powerful Legendary Super Saiyan form. In this form, Broly's muscles swell slightly, his hair assumes a neon blue hue with purple tint (completely purple if in a dark environment, such as his first fight with Goku), and his skin pigment is dulled. When Broly encounters Goku for the second time, his anger grows out of control and the crown shatters, allowing Broly to ascend to his ultimate transformation: Legendary Super Saiyan. In Broly - Second Coming, Broly's regular Super Saiyan transformation makes its onscreen debut (in the previous movie, his Super Saiyan form without control device was only seen in a flashback). 
As a Super Saiyan, Broly also gains an unflinching response to attacks. This is first seen when he attacked Goku in his Super Saiyan form and was completely unfazed by everything that Goku threw at him. This is especially evident when Goku landed a kick to his face and slightly bloodying his mouth, only for Broly to shrug off the injury completely and lick the blood off his mouth, to Goku's disgust. As such, Goku only survived this encounter by running away for the most part. This unflinching response reappears later on when Super Saiyan Vegeta throws a kick directly to his neck followed by a powerful energy blast to his back, both of which had no effect whatsoever.
As the maniacal Legendary Super Saiyan, Broly's strength and speed extraordinarily excel that of any Super Saiyan, and he was described by Vegeta as being the one most powerful Saiyan in all of history. In order to maintain the great increment of muscle mass proportionate to his body, Broly's height also increases by a great amount after transforming, which is shown when the Legendary Super Saiyan form erupts from underneath the flesh of his previous form. 
This form is also one that it is unique to Broly due to being a genetic trait. It is a form that has very little disadvantages and allows Broly to overwhelm his opponents. Broly's power level not only shoots upward tremendously, but it also increases a few more times over the course of the film. Since the power level in this form is so vast, Broly has been shown to take extremely powerful attacks without so much as flinching. The form's effectiveness is shown in full force as he fought three Full-Power Super Saiyans, one Ascended Super Saiyan, and a Super Namek all at the same time while remaining in control of the whole fight, with his opponents being unable to hurt him in the least. 
It was never stated how Broly Achieved Super Saiyan 3 but in this for m Broly speed, muscle mass, height, and power increase tremendously. Broly is the only Super Saiyan 3 that can keep gaining energy in this form also his energy doesn't run out by keep using massive energt attacks such as seen fighting Vegeta.