DIO's Stand is The World; a humanoid Stand that specializes in melee attack roughly equal, if not superior, in its immense force and speed to Jotaro Kujo's Star Platinum.
About a year after gaining his Stand, DIO discovered that it is capable of stopping time. At first, he could only do this for a very short amount of time, but by the end of
Part 3, he is able to stop time for a maximum of 9 seconds. This duration would have continued to develop had DIO not been defeated. When stopping time, DIO gives the impression that he is teleporting or otherwise moving at impossible speeds.
The ability is best known for DIO's activation and cancellation phrases
THE WORLD, Time, stop! and
Time resumes.
Mastery
Having had ample time to rest and train with The World, DIO is shown to have been thorough in exploring his Stand's abilities. Case in point, it was during an experiment session during which DIO sought to test the limit of The World's speed that he discovered his time stop ability.
To give himself an advantage, DIO has tried to keep the ability of The World a secret, only using it at key moments to psych out an opponent and perform incomprehensible sneak attacks, as well as only trusting its secret to a few confidants such as Enya the Hag and not hesitating to eliminate her as soon as she remotely risked to inform the Joestars of his timestop power. However, as soon as they understood its ability, DIO dropped the secret and showed a great degree of confidence about the supremacy of his power, ultimately not caring about his secret as he was convinced that no one could do anything about it. Thus, he began to liberally stop time against Jotaro. Thanks to the free time-frame of action granted by The World, DIO has made it possible to instantly reposition himself to avoid attacks or set himself up to attack, kill enemies instantly, or even displace his opponents to toy with them.
DIO has shown a high degree of control over The World, using it to battle Jotaro's Star Platinum to a standstill, but showing superior technique in hand to hand combat by using low kicks to unbalance Star Platinum or feints to out-punch Star Platinum. However, his Vampire constitution means that DIO never showed the same care at using The World defensively at he preferred to avoid being hit at all and regenerate by sucking blood.
Unlike practically every other Stand User, DIO has sought to improve his Stand's capabilities. He notably wanted the Joestar to come to him so that he could suck the blood of a Joestar and sync himself up with Jonathan's body to further improve his time stop ability. Araki indeed stated that DIO had the potential to stop time indefinitely. Moreover, DIO had searched a way to unlock a power even more powerful than The World, using esoteric knowledge to divine a plan to create another mightier Stand.
Jonathan's Stand
Due to an awakening power within Jonathan Joestar's body, DIO is capable of using a Hermit Purple-like Stand which allows him to create psychic images, be it on photographs or crystal balls. Due to the connection he has between Jonathan's body and his descendants, DIO is also able to sense the presence of other Joestars and can use this to track their position. He is even able to tell when Joseph uses Hermit Purple to take a psychic photograph of him, and instinctively knew that his acquisition of a Stand also awoke Stand abilities in Jonathan's descendants.
Superhuman Strength: Dio attains massive strength as a Vampire, allowing him feats such as forcibly walking on walls and single-handedly deflecting attacks such as Hierophant Green's Emerald Splash (volleys of substantially-sized emeralds flying at almost bullet speed). After absorbing Joseph's blood he is powerful enough to pick up and drop a steamroller on Jotaro.
Superhuman Speed: Dio also possesses superhuman speed and agility. At one point he was described by Speedwagon being faster than a cheetah.
Superhuman Senses: Demonstrated when placing his head on the ground to hear Jotaro's heartbeat, despite being a few meters away, Dio appears to have senses beyond human level.
Regeneration: Dio can regenerate his body faster than fire can consume it. His incredible vitality is maintained by consuming human beings (or their blood), which he commonly does by piercing them with his fingers. Like all
JoJo Vampires, Dio sucks blood through tentacles in his fingers and has been seen at least once drinking blood from an unnamed girl. His body is able to live even after having vital body parts amputated and he can also control his detached body parts. The extent of Dio's own survivability is demonstrated when he could continue as just a head.
Space Ripper Stingy Eyes: Dio is able to pressurize bodily liquid in his eyeballs and then create small openings in his pupils, eventually unleashing two fluid jets powerful enough to slice through stone.
Vaporization Freezing Technique: An ability Dio utilized after learning of the Ripple energy and the danger it presents to him. By vaporizing the moisture in his body, he can absorb heat from any living being he is in physical contact with and freeze them. This ability can be circumvented by Ripple being channeled through items and fire. Dio loses this ability after his original body was destroyed.
Fusion: Dio possesses the ability to graft the body parts of different beings together, using this to create half-man half-beast pets. Dio later used this ability to graft his head onto Jonathan's body.
Flesh Buds: Introduced in Stardust Crusaders, Dio is able manipulate his hair to create parasites that he can insert into a human's head. The Flesh Bud will pierce through the skull into the part of the brain, making the afflicted compliant to Dio's charisma. As explained by Joseph, the parasite will gradually eat the inflicted's brain. If someone tries to take out the spore, which can prove fatal if it's not carefully removed, the Flesh Bud will sprout tentacles in an attempt to invade the intruder's brain. If the vampire wants, he can give permission to someone to activate the spore's tentacles anytime he wants if close to it. The spores possess another effect in case DIO himself ever dies. According to Keicho Nijimura, his father who was implanted by the spore underwent a mutation into a greenish animalistic form by having DIO's cells inside his body. Presumably, this is a side effect that the rest of the surviving Stand Users that DIO had implanted his spores inside of would suffer from.
Hypnosis: This ability was used twice on Jack the Ripper and Poco, respectively. In the case of the former, Dio hypnotized Jack to convince him to join as a servant, allowing Dio to drain his blood and turn him into a zombie. Poco was manipulated to lure Jonathan into a trap, though his consciousness returned after being subjected to Jonathan's Ripple.
Healing: Dio also seems to possess the ability to heal other people's wounds as he was able to completely cure Pucci's wounded foot by simply touching it. However, the origins of this power remain unknown.
Intelligence: Dio is naturally intelligent, displaying cunning and perceptiveness as well as imagination repeatedly.
As a child and teenager, Dio Brando managed to achieve academic excellence with ease, having planned to graduate from university as a top law student.
Otherwise Dio is a cunning villain and proficient tactician in combat. Dio almost managed to get away with two murders, bidding his time in order to have a perfect alibi and was only discovered by accident. Upon his return from the bottom of the ocean, DIO built in six years a powerful criminal empire spanning over several continents and which brought him many riches. In a fight, Dio is particularly cunning and perceptive, his ruthlessness making him able to exploit dishonorable and downright inhuman tactics to get ahead, such as leading his enemies into a trap, using hapless civilians as projectiles and sources of energy, or plain sneak attacks. Dio has the habit of analyzing his opponents and determine quickly a counter to their strengths, such as freezing blood in order to stop the flow of the Ripple, or forcing Jotaro's bluff by throwing multiple knives from all direction so that he's forced to act during the stopped time.
Naturally ambitious, Dio constantly seeks to improve himself and meticulously studies his abilities to make the most of them. As such, he developed a freezing power akin to the Pillar Men's Modes in just a month, and in six years, discovered enough about Stands to be able to fuse several together with souls in order to create the ultimate Stand. Arguably his most successful move, Dio experimented on how his vampiric powers allowed him to fuse two organisms together, and used that knowledge to steal Jonathan's body.
Though he doesn't show it often, Dio has become a natural philosopher, arguing about the human condition with multiple people.
Toughness: All prior to becoming a Vampire, Dio was already an able bare-handed fighter; A skill he says he developed in the slums of London. A good amateur sportsman, during a rugby game as a young adult, he is shown to have developed high athletic ability (as well as fantastic muscle mass).
Charisma: Dio is a cunning and charming individual. In addition to Stand Users, whom Avdol and Joseph suggest he recruits through sheer charm or charisma, he has seduced many women through his life.
Knowledge: Throughout both his humble youth and tempestuous maturity, Dio is often seen reading. During his pre-teens, he is seen playing chess with adults. In
Part 6, in conversation with Enrico Pucci, he is shown to have accumulated some wisdom within the world of Stands. Importantly, Dio is able to concoct a plan, contained in his diary, incorporating vast, unknown information as to the deliberate creation of Stands of perfectly specific abilities.
Spiritual Connection: After stealing Jonathan's body, DIO began to share a spiritual connection with Jonathan's living descendants. He notably was instinctively aware of their presence and their well-being, allowing him to track them across Cairo. Joseph mentions that DIO probably cannot distinguish between him and Jotaro, and only feel their presence.
Weaknesses
Vampiric Body: All of this, however, is at the expense of having a body sustained by sheer willpower alone, rather than vital energy. A sufficiently powerful force of vitality - specifically sunlight or the Ripple - will negate the sustaining force's presence and disintegrate the long-unliving body.
Jonathan's Body (former): When he first acquired Jonathan Joestar's body and resurfaced from the ocean, he was unable to use the full power of his Stand, and had to acquire blood from a live Joestar to compensate and fully synchronize. Once this weakness was negated, he managed to grow significantly stronger, as did his Stand.