Diavolo/Misc

Golden Whirlwind
Diavolo appears as an enemy in Chapters 12 and 13 (as "The Boss", where only his silhouette is seen), as well as 18 and 21, where he utilizes King Crimson to, in the game's perspective, alter time.

In Chapters 12 and 13, he just "teleports" near the player, pretty much how a normal person would see the effects of King Crimson, he also uses a strong hook that crosses the player's body and then throws them (simialrly to his attack on Buccellati in the manga) and punches the floor trying to hit the player with stones.

During Chapters 18 and 21 when Diavolo uses King Crimson, he creates a "slow motion" effect on the screen (with inverted colors), where only Diavolo can freely move, making this version Diavolo's point of view during King Crimson's effect. In Chapter 21, the slow motion effect can be enabled when activating Giorno's Gold Experience Requiem.

All-Star Battle (PS3/PS4)
Diavolo is a playable character in All-Star Battle. As one of the seven main antagonists, Diavolo is stronger than most characters and is by far the strongest due to being able to cause more damage per singular hit, though his lacking moveset limits the combos that can be used. His Stand, King Crimson, is one of the more dangerous Stands in the game due to its Epitaph sub-ability and raw strength. King Crimson's power also works automatically as Diavolo's dash, if the player taps forward two times in a row, Diavolo will "skip" time and appears a little more forward than his original position (the same goes to tapping back-forward or left and right sides). Any moves that activate King Crimson's ability are counters; If the enemy hits Diavolo during one of his poses, the screen will enter into King Crimson's world for a short period of time (similar to the first time Bruno Buccellati was attacked by the Stand), during this time the opponent is unable to move, leaving them open to any attack made by Diavolo. The time erasure immediately ends when he lands an attack.

Diavolo's HHA activates Epitaph, allowing him to see into the future with 100% accuracy. While in this mode, Diavolo dodges most of the enemy's attacks automatically with a Style Dodge without depleting any of the Guard Gauge. Diavolo's GHA, as with his other time-erasing abilities, works as a counter-attack: If Diavolo gets hit by the enemy, his ability will activate and reveal that what the opponent actually hit was their future selves, with Diavolo appearing behind them shortly afterward as King Crimson delivers a powerful chop. Notably enough, this GHA deals roughly 40 - 45% of the victim's health in damage, making it the most powerful Great Heat Attack in the entire game.

Diavolo is the only villain from Part V to appear in the game as a playable character and also the only character to have 2 characters appearing during his intro (Diavolo and Doppio). Diavolo's first alternate costume reflects his initial appearance as "The Boss", while his second features the football team T-shirt he wore to disguise himself and kill Abbacchio. For two of his victory poses Doppio is used instead of Diavolo, and Doppio speaks several of his own (his "phone's" ringtone, answering the phone, his statement about the world being filled with idiots, etc.).

Eyes of Heaven (PS3/PS4)
Diavolo and Doppio were confirmed for Eyes of Heaven alongside their daughter and Bruno.

Touja_romajint
He is paired with Joshu Higashikata in the Eyes of Heaven touja_romajint, but was eliminated in the preliminaries by Bruno and Trish.

Trivia

 * Diavolo's character was likely inspired by the song "21st Century Schizoid Man" by King Crimson, as he is a 21st century man and his two personalities share schizoid traits. Furthermore this song and Epitaph were released on the same album, In the Court of the Crimson King in 1969 and together as singles in 1976.
 * Additionally, Diavolo's theme in All Star Battle is clearly based off of King Crimson's "Neil And Jack And Me "
 * Given the circumstances of his defeat, Diavolo is neither dead nor alive. He is in an endless cycle of deadly situations. Along with Kars and Magent Magent, he suffers a "fate worse than death", condemned to never die.
 * Additionally, Diavolo's defeat, while intentional or not, is religiously symbolic to the foretold defeat of Satan in Christianity. Giorno, the son of "God" (Dio), defeats the "Devil" (Diavolo) and condemns him to suffer endlessly for all eternity.
 * Diavolo is the second antagonist to have a Stand whose key ability involves chronokinesis and the third overall to have chronokinesis.  The first is Dio, who can stop time, and the second would be Yoshikage Kira's Killer Queen's Bite the Dust, which rewinds time.
 * According to a Top 10 List published in Weekly Shonen Jump in 2000, Diavolo is Araki's second favorite antagonist and 4th favorite character overall.
 * Strangely, despite his fervent desire to destroy any and all things connected to him that could have exposed his identity (up to and including his own daughter), he spared Donatella.