In the Yu-Gi-Oh! anime, most of the dueling done of Yugi's behalf was from the Pharaoh, Atem. However, not every last bit of it. There were a few notable exceptions during which Little Yugi took the helm and did the dueling himself. When he did this, though, something interesting happened.
He didn't just use Atem's cards. Instead, he had his own deck full of unique cards that Atem never touched. One of the most notable examples of this is Gandora the Dragon of Destruction, a standby for Yugi.
Gandora the Dragon of Destruction was always used as a kamikaze card for Yugi. As soon as Gandora was brought out onto the field, it was already on its way out, along with every other card on the field. While this is one of the few times that an anime card was weaker than its real-life version, this still busted Yugi out of plenty of tough spots, and it always showed up when Yugi was dueling solo.
Silent Magician is a level card that enhances its power with every single card that the opponent draws. This is a great analog for Yugi, as he grew progressively as the show progressed. This was one of Yugi's most important monsters during the Ceremonial Duel with Atem, but this isn't the only Silent monster that Yugi has in his deck, there is one additional one.
Silent Swordsman functions basically the same as Silent Magician. This card grows a stage during each standby phase, and also starts at 1000 base attack points, growing by 500 for each level.
While Card of Sanctity or Pot of Greed is a great way to quickly level up Silent Magician, Silent Swordsman isn't going to grow until it's ready, sacrificing a bit of utility in the process.
Apple Magician Girl first debuted in Dark Side of Dimensions, and is part of the sub-archetype of the Dark Magicians, being the Dark Magician Girl group. Apple Magician Girl is able to summon another stronger Magician Girl to take a hit for her in battle, and the attacking monster is weakened in the process. Additionally, upon destruction, she can bring 3 Magician Girls from the graveyard to the hand.
Lemon Magician Girl is another Magician Girl that debuted in Dark Side of Dimensions. Save for having some gigantic earrings, she has the ability to allow the player to sacrifice a Magician Girl to add a spellcaster from the deck to the hand. In addition, she can special summon a spellcaster from the hand to take a hit for her, though their effect is negated. The attacking monster loses half of its attack points.
The Magnet Warriors are cards that both Yugi and Atem used individually of one another. The cards are basically able to separate and come together as they please as long as they're all on the field.
The cards are a pretty strong force when they all work together, coming just shy of 4000 attack points when combined as Valkyrion the Magna Warrior. Otherwise, they're just very okay monsters on their own, nothing special.
Summoned Skull is yet another card that both Yugi and Atem used separately. Originally gifted to the pair by Yugi's grandpa, this card saw a lot of play in Duelist Kingdom before it was mostly retried, though Yugi brought it back for the Ceremonial Battle. Other than that, this is a vanilla six-star monster with 2500 attack points with no effect. Beefy, but that's all it has going for it.
Watapon, which is a card that looks like it was literally created to be used by Yugi, can be special summoned out onto the field if it is added to the hand by an effect. While Atem did use this card in the Pyramid of Light movie, this is primarily more of a Yugi card than anything. This card still didn't see much play, however, and would be destroyed pretty soon after being summoned out onto the field. It's cute, at least. That just can't be denied.
Marshmallon is an angry little boy that has an absolutely wild set of chompers ready to bite down on all who would dare oppose Yugi. It's a card that inflicts 1000 points of damage when it is attacked while face down, and cannot be destroyed by battle out of pure spite. What a little king. It's a nice wall if needed, and is pretty cute when those horrible teeth aren't visible. Yugi used this card a few times to bite through all who even dare to think of trying him. It worked, usually.
Finally, Curse of Dragon is another card that Yugi and Atem both used separately. It follows a similar arc to Summoned Skull, being a key player in Duelist Kingdom before being mostly retired from rotation. Curse of Dragon is a vanilla five-star monster with 2000 attack points. Really just doing the absolute bare minimum to qualify for a tribute, huh? Doing great Curse of Dragon, doing absolutely great.