Unlike his counterpart of the original series, who serves as the serious, wise, determined, and protective darker half of Yugi, Yami Yugi is a lot more obnoxious and careless in this series. Like Yugi, he tends to be sarcastic and disbelieving of the plot lines of the episodes. He often uses Egyptian terms for surprised exclamations ("Holy Ra", "Sweet mother of Osiris!", "You son of a Sphinx!", "Holy Mumra!", "Tell it to Anubis!") He has been referred to as Atem, Yami, Nosferatu, Pharaoh, The Artist Formerly Known as Pharaoh, Yugi's Sexy Alter Ego, and Dan Green throughout the series.
In Binary Sunseto, it is revealed that he owns Joey and Tristan, as Tristan tells Joey he "signed their lives away" in Season 1, while they were freaking out over a snake. Yami sees Téa as his "handmaiden."
There are occasions where he is implied to be gay or bisexual. In "Cliffhanger", the episode with the Gay Clown, he says, "If you're a ghost, then I'm straight!". In "Yami of Darkness", he asks to spend time in front of the mirror to apply makeup, to which Yugi responds that he is "such a slut". In "BBT The Abridged Movie" he and Yusei constantly exchange lines about "riding" which is implied to have a romantic meaning, to which Yusei says "no homo". The third time this line is said, Yami says "All of the homo".
He has also defended his ambiguous sexuality in "Rocky VII" when he thought Pegasus was saying they have something in common by being pedophiles. He did show his straight side by admitting he would have "Hit that" when he was near Dark Magician Girl.
Despite Téa's feelings for him, he displays little interest in her (even calling her a whore on occasion). However, after Téa admits to finding brainwashing people fun, Yami agrees, saying they have more in common than he thought. In "The Man Who Would Be Steve", Téa seems to arouse Yami when she's a brainwashed Steve ("Tea has been Steved! This is terrible, and yet strangely erotic").
Similarly to the original series, Yami Yugi does seem to have an innate intuition on how to defeat opponents when playing card games. However, this intuition may have nothing to do with card games. For example, Yami defeats Pegasus by summoning "Little Kuriboh impostors," taking advantage of Pegasus's weakness for "Yu-Gi-Oh! The Abriged Series." In Season 2, he immediately recognizes the Rare Hunter's strategy of summoning Exodia, but his reason is that "if I were a generic villain with no genuine backstory, that's what I'd be doing too." Against "Steve" Arkana, he more or less defeats Arkana by ruining every plot twist in movie history, though thankfully the vast majority of these spoilers are cut out for the benefit of the viewers. Despite coming from ancient Egypt, Yami occasionally references modern-day celebrities and movies, such as Lady Gaga (when he lived in ancient Egypt) and Star Wars.
A common running gag is that, regardless of being the main duelist of the series, he sees Duel Monsters as a card game that shouldn't be taken so seriously and also mocks the strange plays he made during Duelist Kingdom, claiming to cheat.
Although nobody knows his real name, everyone seems to instinctively know he's a Pharaoh from the start. In the Fake series end, he states his real name to be Dan Green (Yugi and Yami's voice actor in the actual series). LittleKuriboh still uses the name Dan Green in a couple of short videos using a stuffed doll of Yami. He also states in "The Evolution of Abridging" that his full name is Yami Victor Yugi, and also says that he hates his mother for naming him this and ruining the alliteration.
In "Final Deathstination", he showed his true uncaring side by attempting to kill Ryou Bakura with Slifer the Executive Producer (much to Odion's, who was impersonating Marik, surprise). Although this probably just reflects how most of the characters felt about Ryou. He asked Bakura "Any last words before Slifer toasts your ass?", to which Bakura replied, "I want my mummy." Yami said that would do, then attacked him. Yami also likes to apparently Mind Crush people, even using one against Joey in his duel before Pegasus. In the original series, he did Mind Crush people with his shadow magic, but he didn't do it for fun, as it was a punishment he would use against bullies that would attempt to hurt his friends beforehand.
In the Abridged series, he also doesn't care much for his friends, except for Yugi. In one scene he even called them "ungrateful brats." However, he did refer to Joey as his only other "friend" when he and Yugi were stuck in the virtual swamp in the Virtual World. Actually, the abridged Yami behaves a lot like the Anime Kaiba who lived by similar principles.
Yami seems to have a problem with bizarre archetypes. He questions why Jean Claude Magnum's deck was full of ninjas and, in a cameo in "Atop the Fourth Wall", why the comic "Bimbos in Time" had so many bimbos in it.
During the "Leather Pants" Special, he claims that his powers come from his leather shoes. As noted in the 'Yugi VS Jaden' Special, he also sees "there is nothing girly about the Dark Magician Girl" and feels that "only real men use Watapon" and that he is so conceited that all of his opponents could swear he cheated during a duel.
Despite his uncaring cold side, Yami Yugi does indeed care about his friends, especially Yugi, going out of his way to save them and keep them out of trouble even if they aggravate him. This was shown when he tried to defend Joey after he lost to Duke Devlin and when he protected Joey and Mai from Mega Ultra Chicken's (the Winged Dragon of Ra's) attack.
Although he argues with and pokes fun at Yugi, compared to his canon counterpart, he does care a lot about Yugi, which is clearly seen in Season 4. He was extremely depressed and cried when Yugi's soul was taken by Dartz showing how much Yugi means to him. After Dueling with Yugi in "Right in the Feels" Yami begins to develop some humility, admitting his wrongs and a desire to do better. He often goes between acting like a brother to a father towards Yugi, telling him to clean his room and threatening to punish him if he feels the need to.
In Season 0 Abridged, Yami is much more malevolent and sinister, as shown when he feeds Ushio to giant man-eating worms because he bullied Yugi, as well as laughing evilly. He also declares that he took Kaiba's BFF'S (Big F*cking Freaks) kidneys because he thought that Kaiba stole his grandfather's Blue Eyes White Dragon. He even burned Jiro The Yellow Spider to death for his own amusement, and possibly for hitting Tea. Yami also (bizarrely) is aware of how the characters behave in future seasons, as he found Kaiba's incessantly friendly personality unnerving and even asked why he didn't say, "Screw the rules I have money," in response to "That's against the rules isn't it?" This could be an exaggeration of how Yami acted before Yugi taught him about kindness and mercy in the original series. In Season 0 Abridged, Yami is extremely sadistic, finding his opponents' pain to be enjoyable. He does, however, seem to be oblivious (or just doesn't care) to the danger of his shadow games. During his Shadow Game with Jirou the Yellow Spider, Yami revealed that he pitched the idea for the Shadow Game that he was about to conduct to Mattel, only for it to be rejected because the rules "were confusing and dangerous" something he didn't understand. He also has dated the Devil, but Yami claimed he never returned his calls because he was "too creepy" possibly referencing how his Season 0/early manga persona was disturbing/creepy.
In addition to housing the inactive spirits and soul rooms of Yami and Yugi and granting Yugi knowledge of games, the ability to mind crush people, and other supernatural powers, Yami's Millennium Puzzle also acts as a reading light and a mood ring, as stated in "A New Evil Awises". In "Puzzled Shipping", Yami is (apparently) a Lord of the Rings fan, because he knows about Middle-Earth, the characters, and the theme song. He also forgets about how to use Pot of Greed, which is not difficult to forget because everyone knows how to use it and constantly declares the rules to said card. And, somehow, he secretly has hidden comic books and action figures, which sort of makes him a child at heart, and yet he doesn't have Nintendo in his soul room. in Roof Ralph, Yami states that he would never be seen dead carrying another person on his shoulders. Later in the same episode, Yami loses his "shoulder virginity" to Rafael. Yami also hates birds as shown in the date scene with Tea he says "f**king birds!"