We do NOT need another complex ban. [The first one should never have existed, Drizzle should have been banned outright, especially as it's still a powerful, massivly centralising force in the metagame]
There is only one pokemon with Magic Bounce and Baton Pass.
This pokemon is Espeon.
Hence, Espeon is broken. It's the same logic as why we didn't do Speed Boost + Blaziken like some people asked, because it's part of the same pokemon.
As long as Espeon remains the sole pokemon with the MB + BP combination, there should not be a complex ban. Espeon is the one at fault. [And, to be honest, Espeon's Base 115 Speed dosen't help things. I doubt that combo would be broken with Xatu]
This logic is why I nominated Espeon. Baton Pass in itself is not broken. It wasn't broken with Shell Smash around, although it was annoying. But Magic Mirror thrown in broke it.
For argument's sake, let's say Mew got Magic Bounce as it's Dream World ability as well. And, obviously, Mew broke Baton Pass with that. In this situation where there are two broken pokemon with the combination, then I would support a Magic Bounce + BP ban.
*Note this may not be the best argument, because MB Mew would probobly be broken outright, hence, removing Espeon's partner, nessitateing an Espeon ban again*
But as long as Espeon is alone, we should ban not Baton Pass, not BP+MM, but the broken factor, which is Espeon.