Crossovers

A crossover is the placement of two or more otherwise discrete fictional characters, settings, or universes into the context of a single story. They can arise from legal agreements between the relevant copyright holders, unauthorized efforts by fans or common corporate ownership.

Down bellow are some lists of Crossovers in Idea Wiki (by Author/User).

Iago PUC

Crossover title	Featured Franchises	Summary
Marvel's Spider-Man: Webbed Champion episode arc "Legendary Universes"	Marvel Comics' Spider-Man Lucasfilm's Star Wars Sega's Sonic the Hedgehog Hasbro's Transformers Nickelodeon's Teenage Mutant Ninja Turtles	To prepare himself for the Regent's threat of war, Spider-Man and his fellow Champions team up with the Jedi Alliance, the Mobian Freedom Fighters, the Autobots and the Ninja Turtles to destroy the missing Oscorp products (which fell in the hands of villains) and solve the origins of Richard and Mary Parker's secret projects.
Marvel's All-Star Multiverse	Marvel Comics' Spider-Man Lucasfilm's Star Wars Sega's Sonic the Hedgehog Hasbro's Transformers Nickelodeon's Teenage Mutant Ninja Turtles	A follow-up sequel to Marvel's Spider-Man: Webbed Champion, it follows the Avengers, the Jedi Alliance, the Mobian Freedom Fighters, the Autobots and the Ninja Turtles working together against new threats following the opening of the Multiverse Star, and the arrival of the Skycruiser Commandos.
Marvel/DC Heroes Unite!	Marvel Comics DC Comics	When Thanos and Darkseid merge together as Thanoseid, whose existence threatens their both universes, the superheroes from Marvel (the Avengers, the X-Men, and the Guardians of the Galaxy) and DC (the Justice League and the Teen Titans) work together and alongside a Rookie hero/heroine to defeat him and stop a war between their universes' villains.
Justice League Dark: Mortal Kombat	DC Comics' Justice League Dark NetherRealm Studios' Mortal Kombat	A follow-up sequel to Justice League: Battle for the Multiverse and Mortal Kombat Legends: Scorpion's Revenge, the film features John Constantine and his faction of the Justice League working alongside Raiden and the Defenders of Earthrealm as well as Lobo and Scorpion to defeat Gideon the Black Knight, who has taken control of the remnants of Darkseid's armies and a faction of Outworld with the goal to bring darkness and death to both universes. Their quest leads them to participate on a new tournament for the fate of their dimensions.
Marvel's Transformers: Assemble and Roll Out	Marvel Comics' Avengers, Spider-Man and Guardians of the Galaxy Hasbro's Transformers	When a small prototype of the Space Stone merges within the Allspark, the universes of the Marvel superheroes and the Transformers become linked to one another. Now Earth's superheroes (consisting of Spider-Man and his fellow Champions, the Avengers and the Guardians of the Galaxy) and the Autobots work together to stop a war between Earth's supervillains and the Decepticons which threatens their both realities and to defeat a new common enemy which emerged from the Space Stone and the Allspark.
Comic Con Incorporated	Several	The series is primarily set on Comic Con Incorporated (or C.C.I. and Comic Con Inc.), a fictional summer resort and 5-Star hotel where comic book characters from different universes enjoy their vacations and summer holidays after doing their daily activities in their worlds. The series features an ensemble cast of notable characters from several comic book publishers (including the Marvel and DC Comics Superheroes), with some characters being managers of the hotel, and most of them being roomers. Ms. Marvel / Kamala Khan, DC Comics' Terra and Archie Comics' Sabrina Spellman from the Archie Comics' fantasy comedy series Sabrina the Teenage Witch are featured as main protagonists. Characters who were introduced outside the comics (such as Sega's Sonic the Hedgehog, who appeared in Archie Comics, comic book characters from stories currently being made by IDW Publishing, as well as Alien and Predator, who were featured in Dark Horse Comics) also appear.
Sonic and the Tomb Raider	Sega's Sonic the Hedgehog Crystal Dynamics' Tomb Raider	Having moved his way from San Francisco, USA to London, England, Sonic the Hedgehog earns a new human friend with a teenage Lara Croft, who shares her home with him. The two undergo a series of adventures around the world while discovering mystical relics and standing against Jacqueline Natla and Dr. Robotnik; both seeking to capture Sonic for his superhuman speed powers, overthrow Lara and take over the Croft Family's fortunes.
Justice League: Rings of the Force	DC Comics Sega's Sonic the Hedgehog Lucasfilm's Star Wars
The Invincible Boys	Invincible (2021 TV series) The Boys (2019 TV series)	Set after the events of Invincible Season 1 and The Boys Season 2, a hyper-dimensional relic begins linking their both dimensions with one another, putting Mark Grayson / Invincible in conflict against the Boys, with Billy Butcher believing that the Guardians of the Globe are invaders (and more false heroes like the Seven), while the Seven try to form a new alliance with the Guardians of the Globe. But when Omni-Man and Homelander clash against each other for control over the relic, resulting in battles which threaten mankind, Invincible and the Boys must put aside their differences, work together to stop their Earths' impending doom, and fend-off a common foe who is orchestrating the issuing chaos using the Global Defense Agency's Reanimen technology and what remained from Stormfront.
Sonic and Marvel Superheroes: Multiverse Speedstorm	Sega's Sonic the Hedgehog Marvel Comics	Following the events of Marvel Superhero Adventures: Intergalactic Grand Prix and Sonic Prime, superheroes continue their usual activities after winning the Intergalactic Grand Prix, whereas Spider-Man and his friends discover that the Infinity Stones are linked to the Paradox Prism, leading to a multiversal encounter with Sonic the Hedgehog and his friends, as the Grandmaster and Dodon Pa host a new racing event called the Multiversal Grand Prix. The two factions also embark in a new adventure across the Multiverse, and a battle against their old enemies, as well as a new threat to both universes.
Iago PUC's Marvel Heroes franchise

MarvelDCandFantasyFanBoy12

Crossover title	Featured Franchises	Summary
PlayStation All-Stars Battle Royale Extreme
Marvel vs. Capcom: Conquest
Marvel vs. Capcom: Glimmer of Tomorrow
Cyber Forces

35Baragon

Crossover title	Featured Franchises	Summary
Godzilla: New Age of Monsters	Godzilla, Gamera, Ultraman and various other tokusatsu characters	Toho's greatest creation, Godzilla is back in an all new animated series, featuring many of Toho's monsters, even monsters from the Gamera film series and the Ultra series.
The Dawn of Godzilla
Multiverse Unity: The Dawn of Monster Kid and Young Justice

PerkerP

Crossover title	Featured Franchises	Summary
Tournament Doofus	Mickey Mouse, Looney Tunes, various other Disney and Warner Bros. characters	Five famous animated characters, Bugs Bunny, Mickey Mouse, Roger Rabbit, Tom and Jerry are the runners of the Great Cartoon Championships. They get into confusing situations, as they try to keep the tournament as great as ever.
Steven Universe: The Tournament	Various Warner Bros./Cartoon Network, Disney and Paramount/Nickelodeon characters	When Steven is invited to the biggest cartoon sporting tournament event of all time, he's excited to make new friends and become a champion - but its easier said than done.

Joint ideas

Crossover title	Featured Franchises	Summary
DC vs. Sega and DC vs. Sega: Aftermath	Various superheroes in DC Comics Various Sega video game characters
Sega All-Star Fight Club	Various Sega video game characters
Pokémon Justice	DC Comics' Justice League and Teen Titans Nintendo's Pokémon franchise	The series is set in an alternate reality, where Earth's superheroes co-exist with the Pokémon, with the members of Justice League and the Teen Titans owing their teams of companion Pokémon.
Warner Bros. All Stars: Shadow Attack
Looney Tunes: Acme Arena	Looney Tunes Tiny Toon Adventures Animaniacs Loonatics Unleashed
The Voice Comic Con	Mickey Mouse, Bugs Bunny, SpongeBob SquarePants, and several characters in TV shows, movies, comics, and video games.	The series is set in The Voice Comic Con, an fictional international reality television singing competition (based on The Voice) where several fictional characters from different franchises (comic books, TV series, movies and video games) demonstrate their amazing talents with the songs which suit them the better. Mickey Mouse, Bugs Bunny and SpongeBob SquarePants serve as the show's hosts and coaches. Animated versions of the original hosts and coaches from The Voice make cameos as guests of the show.