One of the most popular pairings is Mega Man and Roll. It's a classic pairing within the Mega Man universe itself, and in crossovers, it can add an emotional depth to the story. For example, if they are in a dangerous situation in a crossover world, their relationship can be further explored as they protect each other.
Mega Man and Samus Aran is also quite popular. The contrast between Mega Man's more robotic and colorful world and Samus' dark and gritty Metroid universe makes for an interesting dynamic. They can exchange combat techniques or work together to defeat a powerful enemy that threatens both of their worlds.
Naruto and Mega Man themselves are often the most popular crossover characters. Since they are the main protagonists of their respective series, fans love to see how they interact. Another popular one could be Rockman (Mega Man) interacting with Sasuke. The contrast between Rockman's more robotic and logical nature and Sasuke's brooding and power - hungry personality can create some interesting dynamics.
Definitely Mega Man and Samus are the most popular. They are the main protagonists of their respective series, so it's natural that they take center stage in the crossovers. Their contrasting yet complementary abilities make for great storylines.
A very popular pairing is Elsa and Anna from Frozen with other princesses. For instance, Elsa and Anna meeting Rapunzel. Their stories of sisterly love can contrast and complement the relationships of other princesses. Another popular one is Ariel and Belle. Ariel's curiosity about the human world that Belle is so much a part of, and Belle's admiration for Ariel's adventurous spirit make for an interesting crossover. Also, Moana and Mulan are often paired. Moana's connection to the ocean and Mulan's military skills can create some exciting storylines when they cross paths.
One popular pairing could be Naruto and Akane. Since Naruto has a big heart and is always eager to befriend others, he might be able to break through Akane's tough exterior and they could form an interesting relationship.
Tweety and Hello Kitty in a crossover fanfiction can also be quite popular. The cute factor of both characters combined with Tweety's sassiness can lead to some really sweet and funny stories. Tweety might playfully tease Hello Kitty, and they could go on little adventures together in a pastel - colored world.
A pairing that has gained popularity is Rukia and Pyrrha. Rukia's cool - headedness and Pyrrha's kind - hearted and strong - willed nature work together well. Their friendship or potential romantic relationship can be a central point in many 'bleach rwby crossover fanfiction'. Additionally, some fans also like the idea of Byakuya and Glynda. Their no - nonsense attitudes and leadership qualities can be an interesting combination to explore.
Naruto and Hermione from Harry Potter is a fairly popular pairing. It combines the magic of the wizarding world with Naruto's ninja skills. Another one is Naruto and Luffy from One Piece. Their energetic and adventurous personalities make for an interesting combination.
Often, Shu and Inori are paired in crossovers as they are the main characters in Guilty Crown. Their relationship is central to the story, so it's natural to see them together in crossovers. Another popular pairing could be Shu with a character from the crossover anime who has a similar power or personality trait.
Some fanfictions might pair Castiel and Cisco Ramon. Castiel's otherworldly nature and Cisco's scientific mind could lead to some really interesting interactions. For example, Cisco could be fascinated by Castiel's angelic powers and try to find a scientific explanation for them, while Castiel could be intrigued by Cisco's tech - savvy ways.
It could be Naruto in his strongest form, like Six Paths Sage Mode. He has incredible power, speed, and the ability to use a wide variety of jutsu. He could potentially overpower Mega Man's weapons with his raw chakra power. However, Mega Man has his own advantages like his adaptability with different weapons and his experience in fighting robotic enemies. But if we consider overall power and the scale of destruction Naruto can cause in his most powerful state, he might be the most powerful.