@PaulHaynek: At least no gag characters.
As for the multiversal stuff, that relates strongly to what kind of premise we go with. The way I see it premises for this kind of thing tend to work out in a few different ways:
The "help" type: Where someone summons people from other worlds to help them, possibly sending them to different universes to accomplish something or fight an enemy.
The "taskforce" type: The characters, or at least roughly half, are all part of a multiversal organization and work to accomplish things for them, such as protecting worlds or hunting down threats.
The "game" type: A powerful being summons people from other worlds to compete in some kind of game, that possibly involves multiversal travel.
As for the multiversal stuff, that relates strongly to what kind of premise we go with. The way I see it premises for this kind of thing tend to work out in a few different ways:
The "help" type: Where someone summons people from other worlds to help them, possibly sending them to different universes to accomplish something or fight an enemy.
The "taskforce" type: The characters, or at least roughly half, are all part of a multiversal organization and work to accomplish things for them, such as protecting worlds or hunting down threats.
The "game" type: A powerful being summons people from other worlds to compete in some kind of game, that possibly involves multiversal travel.