Of the twelve, all but two (Roronoa Zoro and Killer) are Devil Fruit users as well as captains of their respective crews. According to Shakuyaku, one of the Supernovas could potentially be responsible for inspiring a whole new generation of pirates.
With the exception of the Straw Hat Pirates, most Supernovas attempted to avoid the paths of the World Nobles. Coincidentally, all the Supernovas arrived on the Sabaody Archipelago at the same time which caused a series of issues for the Marines. In addition, all of them, except for the Straw Hat Pirates and the Heart Pirates, entered the New World almost simultaneously. Teach and his crew, on the other hand, were already in the New World by the time the rookies were making preparations.
The Supernovas are the top rookie pirates from nine different crews who all chose one of the seven routes along the Grand Line. They are comprised of the captains of the nine crews as well as two other crew mates who also are above the bounty threshold of 100,000,000. They come from all seas - East Blue, West Blue, South Blue, North Blue, Sky Island and the Grand Line itself. They all ended up on the Sabaody Archipelago at the same time.
A common trait they all possess is that they have caught the attention of the World Government and have survived many ordeals that have wiped out other pirate crews along the Grand Line. Though they are all on par with each other as far as threat level is concerned, they represent different views on piracy. To date, their journeys along the Grand Line are unknown, save the Straw Hat Pirates journey, which is the main focus of the storyline, and that the Kid Pirates have caused mass civilian casualties along their way.
Due to a major mishap caused primarily by the Straw Hat Captain, Monkey D. Luffy at the Human Auction House, all of the Supernovas were struggling to evacuate the Archipelago facing confrontations with Marines, an army of Pacifista and ultimately AdmiralKizaru and the large guardian Sentomaru. One by one, they started displaying their unique abilities that made their outrageously high bounties well-deserved. However, the results and circumstances regarding their individual showdowns varied:
The Kid Pirates and Heart Pirates were caught in a battle with a Pacifista. The end of the battle was unseen, but since they reappear during the Marineford Arc, it can be assumed that they either defeated the Pacifista or managed to elude it. Kizaru mentions that the Heart Pirates did a good job running away.
A combination of Basil Hawkins, X Drake, Urouge and Scratchmen Apoo were easily defeated by Kizaru himself and a Pacifista. Since they reappear during the Marineford Arc, they avoided their arrest somehow.
The Straw Hat Pirates were caught between the Pacifista, Kizaru and Sentomaru before ultimately being sent in many different directions by the appearance of Shichibukai Bartholomew Kuma. Luffy ended up transported to Amazon Lily, ultimately becoming aware of the public execution made by the World Government of his adopted brother, Portgas D. Ace, and becoming one of the key players to the following events that transpired in the Whitebeard War; Zoro, on the other hand, did not even witness the war, being on a faraway island.
Only Capone Bege and Jewelry Bonney had little trouble, facing only Marines before supposedly escaping from the area, although the fact that they did not encounter Kizaru should be taken into consideration.
Surprisingly, not a single one of the Supernovas was brought into custody, as they were all seen (save for Zoro and Luffy) at Sabaody watching Ace's televised execution, which may have been in part thanks to the Marines focusing on the Straw Hats. Although some of them may hold grudges against Luffy for the ruckus that he caused on Sabaody, it is unknown if any of them have changed their opinion after learning that he has made it in and out of Impel Down, taken part in the Battle of Marineford, and is Ace's younger adoptive brother and Dragon's son, but after the broadcast from the battlefield was cut, they were seen leaving Sabaody. It remains unknown what the Supernovas' collective reactions are regarding the deaths of Fire Fist Ace and Whitebeard, who was assassinated by the Blackbeard Pirates, who arrived on the scene of the war toward the end.
Near the end of the war, Trafalgar Law and his crew were seen arriving near Marineford with their submersible vessel, apparently with the purpose of rescuing the injured Luffy by assisting his escape and treating his wounds afterward.
Aside from Zoro and Luffy, the rest of the Supernovas were revealed to have traveled to the outskirts of Marineford to witness the conclusion of the war. Apart from Luffy and Law, who were invited to take refuge at Amazon Lily by Boa Hancock, whom they met up with after the war, and Zoro, who was still at Kuraigana Island, the rest of the Supernovas headed off to the New World. Law eventually left Amazon Lily, wondering what the "D." will bring next, but he refused to enter the New World yet as he deemed the battles there too ferocious for now.
Sometime upon landing in the New World, Bonney was defeated by Marshall D. Teach in what used to be the territorial waters of Whitebeard. He attempted to exchange her for a Marine battleship, but she was left behind to be arrested when Teach saw AdmiralAkainu on board the incoming Marine ship and knew Akainu would have no interest in striking a deal for Bonney. Also, upon reaching the New World, the Kid Pirates, while torturing an unnamed crew he defied, read in the newspaper that Luffy had returned to Marineford to pay his respects to his brother and the fallen Marines and pirates, then rang the Ox Bell 16 times, as if declaring a new age of his own (though it was just to grab his crew's attention). At the same time, Bege and his crew were drawn toward a giant black ball in the sky, Hawkins prepared to battle Brownbeard, Urouge had trouble landing on Raijin Island until he was approached by an old woman who offered him umbrellas, Apoo and his crew were running in midair from a pack of savage boars, and Drake decided to take down one of Kaido's subordinates and gain the Yonkou's attention.
Meanwhile, the Straw Hat Pirates, having read the true intent behind Luffy's message, decided to take a two-year training break in order to become strong enough to challenge the New World.
Marshall D. Teach and his crew began stealing devil fruit powers from those who had them, presumably the same way they stole Whitebeard's Gura Gura no Mi ability, and used their captain's knowledge of Whitebeard's former territory to conquer it. Doing this made Teach a major threat in the New World, and the World Government labeled him as Yonko.
Trafalgar Law got his bounty increased to 440.000.000 for yet unknown reasons.At some point during the timeskip he sent one hundred pirate hearts to the World Government, thus gaining the title of Shichibukai.
Eustass Kid, Killer, Basil Hawkins and Scratchmen Apoo also got a bounty increase respectively of 470.000.000, 200.000.000, 320.000.000 and 350.000.000.
Jewelry Bonney was able to escape from World Government.
Oda gave a depiction of ten of the Supernovas (leaving out Zoro) after the two-year timeskip. Blackbeard is also left out of such a depiction.
Before the timeskip, the combined bounties of all Eleven Supernovas equal to 2,152,000,000, the highest combined amount of any known group. It is currently unknown what it is post-timeskip. With the information revealed so far, the collective amount is at 2,800,000,000.
Aside from Killer and Luffy, all the others were named after real life pirates or privateers. While Oda did not intend it at the time, Luffy has a similar naval term via a "Luff". This leaves Killer as the only one whose name has no link at all to any sea-based term or name, and Oda admitted in an SBS he was given his name out of pure laziness.
The term "Supernova" can also be used for any rookie who earned a bounty of over 100,000,000, not just restricted to the eleven, as Bartolomeo was called as such.