The Multiverse Coliseum

( based on the general idea and setting of Reincarnation Colosseum - Using The Weakest Skills In Order To Defeat The Strongest Women And Create A Slave Harem so you don't actually have to follow the story of that if you don't want to because it's just based upon it the idea)

The Multiverse Coliseum a place that allows people from across the Multiverse to fight some are summoned some simply find the way here but ultimately comes down to them fighting each other for those who do not have any skills or special abilities, one or more will be given to them upon their arrival( this includes abilities that belong to various worlds including but not limited to devil fruits, special body both physical and spiritual, and various Energies and elements)) upon defeat the winner gets the defeated as their slave in case of a female winner regardless opponent the a potion or if they already have a skill for it grow a dick with the same circumstances the male loser will be forcibly turned female via another skill or potion ( or feminized if you want)

( as I really don't have anything set up for this aside from the idea take it however you want, go crazy, have fun. Note you can bring characters from anime video games TV shows from whatever sources you want I do ask that you at least put where the characters are from you don't have to but it would be helpful)