Joestar Group

The Joestar Group is a nickname given to the team of protagonists prominent in each part of JoJo's Bizarre Adventure. The group is composed of different members in each part, but generally consists of a JoJo, their "sidekick," and various other allies all following the same or a similar plan of action (i.e defeating DIO or protecting Morioh).

Phantom Blood
The original Joestar Group starts in 1889 with Jonathan Joestar, aided by his allies William A. Zeppeli and Robert E. O. Speedwagon. Although Bruford was originally an enemy, he respects Jonathan after their battle and gives him his sword, Luck and Pluck. Later on, Dire, Straizo, Tonpetty and Poco assist Jonathan in an effort to deter the incoming threat to mankind, Dio Brando.

Battle Tendency
50 years later, in 1939, Jonathan's grandson Joseph, along with his partner Caesar Zeppeli, their mentor Lisa Lisa, and Nazi major Rudol von Stroheim, engage the creators of the Stone Mask, the Pillar Men.

Stardust Crusaders
48 years later, in 1987, Jotaro Kujo, the grandson of Joseph Joestar, is pulled into stopping the reawakened DIO as his resurrection causes Jotaro's mother to fall into a deadly fever. Jotaro, who has now acquired a Stand called Star Platinum, hunts down DIO in Egypt with help from his grandfather Joseph, Muhammad Avdol, Noriaki Kakyoin, Jean Pierre Polnareff and a dog named Iggy.

Diamond is Unbreakable
12 years later, in the year 1999, the illegitimate son of Joseph Joestar, Josuke Higashikata with his Crazy Diamond takes it upon himself to protect Morioh from enemy Stand users after his grandfather is killed. He is aided by Jotaro, his classmates, and a strange mangaka. They target Stand users who use their Stand to harm others such as Angelo, Akira Otoishi, and Yoshikage Kira.

Vento Aureo
In 2001, Giorno Giovanna, the son of DIO, joins Bruno Bucciarati's team of Passione gang members in order to rise within the ranks and overthrow their mysterious boss, who is flooding the streets of Italy with drugs. By doing so, Giorno hopes to set the mafia's moral standards straight again. The group is also aided by Polnareff and Koichi who are members of previous Joestar Groups.

Stone Ocean
In 2011, Jotaro's estranged daughter, Jolyne Cujoh, is incarcerated for a crime she didn't commit and is in a deadlock against the remnants of DIO, led by his most devout supporter, Enrico Pucci. Her goal is to save her father, escape prison, and survive. She is helped by her father, Emporio Alniño, Ermes Costello, Foo Fighters (F.F), Weather Report, and Anasui.

Steel Ball Run
In an alternate 1890, Johnny Joestar along with Gyro Zeppeli rides coast to coast to compete in the Steel Ball Run. They discover the Saint Corpse Parts while racing, which gives them Stand powers and greatly improves their physical abilities. The duo is hunted by many people during the race, including other racers, mercenaries, & even the president of that time.

JoJolion
120 years later in 2011, the tentatively named Josuke Higashikata is joined by his love interest Yasuho Hirose, friends from his past and adoptive family, as they work together to discover Josuke's original identity. Their investigations lead them to uncover the Higashikata Family's deepest secret and run afoul of the mysterious Rock Humans.

Similarities

 * The majority of the groups are not led by the centered JoJo but rather by an ally:
 * Part 1's group was initially led by William Zeppeli before his death, all the while he was teaching Jonathan the basic mechanics of the Ripple.
 * Part 2's group was led by Lisa Lisa, the master of Joseph and Caesar, as well as the strategic leader in the war against the Pillar Men.
 * Part 3's group was led by Joseph, the eldest of them, who initiates the group's goal to find DIO and fight him in Egypt.
 * Part 4's group was led by Jotaro, the main rallying force for the active hunt for dangerous Stand users throughout the part.
 * Part 5's group was led by Bucciarati as the direct superior of every member, plus acting as a father figure to the group in general.
 * Part 6's group is the first group to be led by the current JoJo, Jolyne. She leads the group's moves and commands the respect of her companions.
 * Part 7's duo is a partnership, Gyro and Johnny agreeing to work together to reach each other's goals, however Gyro is the Spin teacher and thus possesses a tacit leadership role.
 * Part 8's group is the second group led by the current JoJo, as Josuke's will to uncover his identity is the main drive behind the duo's actions.
 * With the exception of Part 2 and 4, the majority of those in Joestar Groups dies before the end of their stories with very few carrying over to the next respective part. (i.e. Speedwagon, Joseph, Polnareff, Jotaro and Koichi).

Trivia

 * Though not initially planned, Araki threw around the idea of Hol Horse joining the protagonists during their journey, but opted out due to balance issues with Polnareff's similar character. Araki mentions this is part of the reason Hol Horse shows up multiple times throughout the story and why there is at least one group shot with Hol Horse present.