basically 'make' the tailed beasts as they appear in the comics or something, and randomly put them in people from the village they come from in the manga... and make the jutsu that 'steals' the bijuu and reseals it within something else :O and make the 'stealing' jutsu only activatable if the jinchuuriki is near death... :O make things very very interesting ;) hunt down the Jinchuuriki and try to capture and seal Bijuu within village mates to make your village stronger :O

and as for a generic power for em all, what about 'staged' unlocking, as in partial and full (for Shukaku) and in between, up to the number of tails available for that form... (like Nibi would have Partial, One, and Two[full])... :O