Joey is the male personification of a "dumb blonde". In other words, the parody makes him out to be incredibly stupid. For example, while playing Duel Monsters with Yugi in Bakura’s flashback in Episode 11, he exclaimed "Checkmate! I sunk your battleship!" Despite this, however, he seems to be very able at building good decks. In episode 2, Joey’s deck was so good, Yugi decided to steal it and told him that it was worthless and it needed a few changes. In Episode 17, he even defeated Bandit Keith by copying his "in America" stunt by playing Copycat. He also apparently hates blonde people (ironic given the fact that he himself is blonde), and he doesn't seem to realize when people are insulting him such as when Kaiba states that Joey couldn't duel his way out of the paper bag and Joey retaliates by saying "Hey, you can't insult my friend Tristan like that!." He reveals in the first episode that he has a Brooklyn accent, which he considers inappropriate.
Another significant difference is that Joey bears no compassion towards his sister. This is shown as early as Episode 3, when he receives a video from Serenity about her blindness, but is more upset that it wasn't from Pegasus to take his soul. Also, though he entered the Duelist Kingdom tournament in order to win the prize money; unlike the original, however, he wants the money for himself (and at one point having a monologue to her about "winning the prize money for speaking lessons, so she'll learn how to talk good, like what I do!"), rather than to fund the operation for Serenity and spends most of it forgetting she's alive or blowing off her condition. In Episode 14, when reminded about his sister, he figured he could just use the money to buy a new one. This was debunked rather comically in Episode 19 when he mimicked Kaiba: "Screw my sister, I have money!" In Episode 25, it seems that Joey is excited that his sister is going to be able to see again. In reply, Tristan asks if Joey spent the prize money from Duelist Kingdom on her operation. Joey stated, "Nah. My mom's paying for the operation. I spent the prize money on children's trading cards." Though he does show some compassion towards her in Episode 27 by promising not to let bad things happen to her, but when the operation fails, he goes and steals her trading cards. Though in Episode 39 he declares that he will now stop neglecting her and treat her with the respect he gives his friends (ironically they show up shortly after and Joey calls for security on them). In episode 47 he attempts to comfort her when she is afraid that her character will be written out of the show, though the only justification he could think was giving Tristan and Duke a reason to be there which she thought was terrible. He still maintains his protectiveness over her when he threatens Tristan when the later talks about sleeping with her, claiming if he does "I will kill you."
After his recent defeat from Kaiba, Joey has begun to have some "erotic dreams" about Kaiba in which he himself wears a dog suit, something that he actually seems to enjoy. While he denies it ever happened, in Episode 43 he admits it to Mai. As noted in the credits of the Abridged Movie, he eventually came to terms with his furriness and makes regular appearances at Anthrocon.
Among his gags is the constant "Nyeh!" sound he exclaims when shocked, startled, in pain, etc., but apparently he can't hear himself saying it, as Joey has no idea what Bakura was talking about when he asked him in Episode 40. In Episode 28, he began using the catchphrase "Brooklyn Rage" to show his anger, but Yami tells him that it will never be a popular catchphrase and tells him to stop. It is known that Joey's 4Kids VA Wayne Grayson likes the phrase and has repeated it at various anime conventions. In Episode 31 Joey claimed he had "rage of the Brooklyn variety" putting a new spin on the Brooklyn Rage catchphrase. In Episode 50, he states that he has "a rage which is centered in the western-most county of Long Island, New York. Also known as Brooklyn."
In Episode 12, it is also revealed that he is apparently a fan of both Firefly, a TV show by Joss Whedon (creator of Buffy the Vampire Slayer TV series), and Serenity, its subsequent movie continuation. It is known that Abigail (Safty on Youtube), LittleKuriboh's wife, is a fan of the show. The fact that when Yugi reminds him of his love of Serenity, which Joey took to mean Joss Whedon's movie and not his sister, highlights his disregard for his sister.
It is vaguely implied that he actually caused the death of 'Tristan Taylor's voice' at the end of Episode 8. Whilst he explains that he was "with Tristan's voice when he passed away," he looks himself like he has seen better days, and also gives a somewhat fantastic explanation that Tristan's voice died after running with scissors while drunk, and in the 'Reconstruction' of the event, he reacts to Tristan's voice's death with an obviously nonchalant "Oh no, he's dead."
In Cr@psule Monsters, Joey doesn't seem to remember anything that he and the rest of the gang had encountered before then, not even Mai Valentine. He also tries to claim they're not ripping off Pokémon even though he's riding Baby Dragon and keeps comparing it to Charizard.
In the Other Abridged Movie, Joey develops a passion for getting into fights with other people, claiming to be much more satisfying than card games (clearly a reference to his Shadow Game series counterpart, who was a rebellious man that always got into fights and showed great strength at them). He also calls his fighting style Brooklyn Karate, names his fighting moves like "Surprise Buttsex" (grabbing his opponents from the back) and Joey Punch, although Surprise Buttsex is also a way to show suggestive affection (Yami Yugi claims that Buttsex with him is never a surprise).
Ever since he defeated Weevil in Episode 31, Joey claims he's going to pick off all the minor season one characters in the Battle City Tournament one by one claiming that's how he rolls (a reference to how most of his opponents in Battle City are minor season one characters). He even goes as far as wanting to duel Kaiba, calling him a minor season one character, which makes Kaiba want to kill him.
In Episode 34, Joey is in a censored fight with Marik's henchmen and ends up getting captured. He claims, in this episode, to love 4Kids fight sequences because you can be as violent as you want as long as no one is watching. During his imprisonment he was fooled into signing a "Name Change" contract that legally changed his name to Steve. He is then mind-controlled by Marik.
In Episode 38, Joey admits he has fallen in love with Mai's breasts, though he adds that "They're about as real as a 3-dollar bill." In Episode 43 he actively prevents himself from starting a relationship with her but tries to save her from both Mega Ultra Chicken and Melvin (though Yami saves them both from Mega Ultra Chicken's attack and Melvin scares Joey into leaving).
He does, in fact, care slightly for Bakura, as seen in Episode 40, as he is disgusted when Yami almost kills Bakura and then blames it on Marik, stating that he'll tell everyone what Yami did, all of which he says in an outraged tone ("He didn't make you do anything you asshole! You almost killed Bakura, and now I'm going to tell everyone!"). He is then interrupted by Yami, who says that "Joey has tickets to see Miley Cyrus in his pocket." Joey points out that this is a lie just as Duke Devlin and Tristan tackle him, the latter stealing Joey's pants. As heard, "Tristan! Gimme back my pants!" Yami then says it "works every time." Though at the same time he questions what Bakura is doing in his hallucination in Episode 42 when he sees all his friends.
In episode 50, he passionately defends the Yugioh abridged series from Johnson's attempt to get it banned for copyright infringement. It is also revealed that he once punched Yami for eating his sandwich, he knows that Bandit Keith is really Canadian and not American, dated Duke's fat cheerleader (she claims she never saw him again afterwards, but Joey sites that he's just been busy), and that Baby Pharaoh doesn't like him for some reason.