Normally, I write stories set in a universe where the characters of Marvel and DC all live in a shared universe so that the team-ups between characters from both companies can interact with each other. Not only do I include those characters, but I also include the characters from the 2005 Disney movie, Sky High. For my series of stories, the main characters are this universe's second Teen Titans.

Tim Drake aka Robin (Age 15)
Peter Parker aka Spider-Man (Age 16)
Kara Zor-El aka Supergirl (Age 16)
Kamala Khan aka Ms. Marvel (Age 16)
Wanda Maximoff aka Scarlet Witch (Age 15)
Cassandra Cain aka Batgirl (Age 14)

For this story I have in mind, the Titans are fighting a group of villains at Doctor Strange's Sanctum Sanctorum when the three villains escape with an artifact through a magic mirror. When the Titans follow, all of them end up in Equestria and are ponies as a result of traveling through the mirror. To save Equestria, the Titans must learn to master these bodies and work with the Mane Six to stop the three supervillains and a new mysterious enemy for the ponies of Equestria.

These are the Marvel/DC villains I'll be using.
Marvel:
Amora the Enchantress
Skurge the Executioner

DC:
Starro the Conqueror