In the world of anime, 'Dragon Ball Z: Fusion Reborn' is an excellent crossover. It features characters from different parts of the Dragon Ball universe coming together. Goku and Vegeta's fusion, Gogeta, is a highlight. The story has a mix of action, humor, and the charm of seeing familiar characters interact in new and unexpected ways.
The 'Civil War' storyline is also a top - notch crossover. It divided the superhero community over the Superhuman Registration Act. This led to intense battles between heroes like Iron Man and Captain America, and explored complex moral and political issues within the Marvel Universe.
A 'Doctor Who' and 'Sherlock' crossover is often considered among the best. The Doctor's time - traveling abilities combined with Sherlock's brilliant deductive skills make for a really engaging story. You can have the Doctor land in Victorian London and team up with Sherlock to solve a mystery that has both scientific and criminal elements. Also, a 'Supernatural' and 'Buffy the Vampire Slayer' crossover is cool. Hunters from both shows could collaborate to fight against a greater evil that threatens both their worlds.
A good MacGyver and NCIS crossover fanfiction would likely focus on a shared mystery. Maybe a terrorist group is using both high - tech gadgets (which MacGyver is good at dealing with) and has some connection to the military or naval cases that NCIS usually handles. The story could develop the relationships between the characters from both shows. For instance, Abby from NCIS might be fascinated by MacGyver's homemade tools and try to learn from him, while MacGyver could be intrigued by the forensics work that Abby does.
One great Supergirl crossover fanfiction is 'Supergirl and the Flash: Worlds Collide'. It has an exciting plot where Supergirl and the Flash team up to face a common enemy that can manipulate time and space. The story does a great job of capturing the essence of both characters and their unique powers.
The best crossovers often explore the different power dynamics. Supergirl's super strength and flight compared to the Winchesters' hunting skills and knowledge of the occult make for an interesting mix. There are fanfictions where they exchange knowledge, like Supergirl learning about ancient spells from the Winchesters and the brothers getting tips on how to take down powerful foes from Supergirl.
I really like the fanfiction 'Digimon Crossover: Digital Dimensions'. In this story, Digimon from different universes are accidentally brought together in a strange digital dimension. It has great character development as the Digimon and their partners have to learn to work together despite their differences. A more action - packed one is 'Digimon: Cross - World Battle Royale' where Digimon from all over are forced to fight in a no - holds - barred battle. And then there's 'Digimon and Yu - Gi - Oh: Dueling in the Digital World' which is a really creative crossover with Yu - Gi - Oh characters ending up in the Digimon world and having to use their skills in a whole new context.
Well, a really well - written Meliodas crossover fanfiction is 'Meliodas in the One Piece World'. The story shows how he would get along with the Straw Hat crew. His devilish nature and Luffy's carefree attitude make for some hilarious moments. 'Meliodas and the Attack on Titan World' is also quite good. It explores how his combat skills could be used against the Titans. And don't forget about 'Meliodas in the DC Universe' where he could potentially face off against Superman or Batman.
One great 'best overlord crossover fanfic' is 'Overlord and the World of Magic'. It combines the unique elements of the Overlord universe with a magical world, creating interesting character interactions and a new adventure for the Overlord characters.
In some of the best 'pokemon crossover fanfiction', Pokemon cross over with the world of Naruto. The ninja world gets a new dynamic with the addition of Pokemon. Trainers become like ninja - trainers, and Pokemon battles are incorporated into the ninja battles. Some fanfictions also have a crossover with the world of Attack on Titan. Picture Pokemon helping to fight Titans, it's a really unique take on both universes.
A really cool 'best superman crossover fanfiction' might involve Superman crossing over with the Justice League from another universe. This can lead to some amazing scenarios where he has to adapt to different versions of his teammates and face new threats. It's interesting to see how his powers and character are perceived in these alternate settings.