You're probably right. However, I think that with some balancing the concept could work. It would at least stop the same fights coming up again, and allow you to introduce some new blood. The teams don't have to be based on any continuity. You could put Alucard (Hellsing), Angelus (Buffy) and Blade (Uuuh, The Blade comic series) on a team because they're all vampires or Dovakhin, Captain Marvel (DC version) and Sinestro on a team because they all absorb the power of other, more powerful entities to fight (Dragon souls; Solomon, Heracles, Atlus, Zeus, Achilles and Mercury; Paralax (via the ring) respectively). Sailor Moon, Goku and Jacob from Twilight also could be a team because they're all associated with the moon (I assume werewolves work that way in Twilight) I think that it'd at least add a fresh twist to the concept of a BZT.
Perhaps a spinoff, as it were since it's been so successful ofer the last couple of years.