Johnny is proud, sensitive, and initially cold, finding it difficult to trust others. However, he possesses an intense tenacity and competitive spirit to achieve his goals, seeing things through to the end once he sets his mind to them. Though he appears blunt and detached on the surface, he is deeply emotional and gradually learns to trust and rely on others while traveling with Gyro. His Stand, Tusk, allows him to spin his fingernails and fire them like bullets, growing more powerful as it evolves through different Acts. Specifically, Act 4 utilizes the power of the Infinite Rotation to deliver devastating attacks. He is paraplegic, but after witnessing Gyro's Steel Ball technique, he finds the possibility of regaining the use of his legs.

Gyro Zeppeli has a confident and relaxed personality, often appearing playful and sly. He speaks bluntly and enjoys teasing others, but remains calm and serious when making critical judgments. He is firm in his beliefs and goals, leading his companion Johnny while occasionally acting as a strict mentor. He also possesses a strong sense of justice and responsibility, with a powerful will to fulfill his duties. His Stand, Ball Breaker, utilizes Steel Balls that harness the power of rotation to its limit, delivering immense rotational energy to opponents. He has a distinctive laugh, often chuckling with a "Nyo-ho!"

Diego is highly prideful and competitive, driven by a powerful desire to prove he is the best. He is cold-blooded and will use any means necessary to achieve his goals, possessing the cunning to quickly identify and exploit an opponent's weaknesses. While he appears confident and grand, he harbors deep-seated inferiority complexes and obsessions regarding his past and social standing. His speech and actions are rough and provocative, yet he displays exceptional judgment and horsemanship in crises. His Stand, Scary Monsters, allows him to transform into a dinosaur or turn other living beings into dinosaurs, eventually granting him the ability to transform himself into a powerful dinosaur form.