I think Gokudera and Joey would be a great pair. Gokudera's hot - headedness and his loyalty to Tsuna could contrast with Joey's impulsive but kind - hearted nature. They could get into all sorts of misadventures together. Also, Hibari and Marik could be an interesting duo. Hibari's solitary and aggressive nature might be a match for Marik's more devious and power - hungry side. It would be fascinating to see how they interact and either become enemies or strange allies.
One idea could be that the characters from Katekyo Hitman Reborn end up in the Yu - Gi - Oh world and have to learn the rules of Duel Monsters to survive. They might team up with some of the Yu - Gi - Oh characters like Yugi or Kaiba. Another plot could involve a villain who uses the powers from both universes to create chaos, and the heroes from both series must combine their strengths to stop him.
Joey and Kirishima would also be great. Joey is a loyal friend and has a lot of heart in his duels. Kirishima is all about being manly and protecting his friends. They could bond over their loyalty and have some really fun adventures together, with Joey teaching Kirishima about the Yu - Gi - Oh cards and Kirishima showing Joey some of his cool hero moves.
Yami Yugi from Yu - Gi - Oh is also a strong contender. His Millennium Puzzle gives him access to powerful magic and ancient knowledge. In a crossover, he could use his skills to outwit Pokemon trainers. He might be able to predict their moves and use his cards in ways that would give him an advantage against the Pokemon. He could also form a bond with some of the more intelligent Pokemon and use their powers to enhance his dueling abilities.
It could be Naruto. His huge chakra reserves and his ability to access the power of the tailed beasts would give him an edge. He could potentially use his chakra to power up Yu - Gi - Oh cards in ways no one else could. Also, his ninja skills like speed and stealth could be used during duels in unexpected ways.
It's hard to say for sure, but Naruto could be really powerful. His ability to create an unlimited number of Shadow Clones could give him an edge in a Yu - Gi - Oh duel. He could use the clones to strategize and overwhelm his opponents. However, Yugi has the power of the Millennium Puzzle and his strong connection with the spirit world. So, it really depends on how the crossover is written and what rules are applied.
Ash from Pokemon and Yugi from Yu - Gi - Oh would be really interesting. Ash is a fearless and determined Pokemon trainer, while Yugi is a strategic and kind - hearted duelist. Their different personalities and skills would create a great dynamic. They could learn from each other, like Ash teaching Yugi about the bond between a trainer and a Pokemon, and Yugi showing Ash the intricacies of dueling.
Sasuke could be a very interesting crossover character. His brooding and powerful nature would contrast well with the more colorful characters in Yu - Gi - Oh! Arc - V. He could use his Sharingan to analyze the dueling strategies and might even develop a new form of dueling that combines his ninja powers with the rules of Yu - Gi - Oh! He might be initially dismissive of the card game but then find a new sense of purpose or power within it.
Naruto and Yusei would be an interesting pair. Naruto's exuberant and determined personality combined with Yusei's cool and calculated nature could lead to some great interactions. They could learn from each other's strengths and overcome their differences to face challenges together.
Then there's Albus Dumbledore. His vast knowledge of magic and his powerful spells, such as the ability to perform powerful defensive magic and his wisdom in handling magical artifacts, could make him a force to be reckoned with. In a crossover, he could potentially study the Millennium Items and find a way to use their power in harmony with his own magic, making him a very powerful character in the combined universe.
It could be Yami Yugi. He has the power of the Millennium Puzzle and is an extremely skilled duelist. In a crossover, his ability to strategize and his connection to the ancient Egyptian magic within the Yu - Gi - Oh world could give him an edge. He could potentially use his skills to outwit the dark wizards in the Harry Potter universe. His confidence and the power of his cards could make him a formidable force against even the likes of Voldemort.