I like this idea.
If i may make this suggestion:
9 People chosen at random (9/60,000+)
The mount versions of themselves would be removed with a refund to any who have them
Those 9 people could spend DK points on Bijuu (spelling?) training, after X points, the Bijuu becomes controlable.
When the Bijuu is used, the user gets a great bonus (I say depending on the Bijuu).
When the Bijuu is used, the user starts with 50% health and turns the next day and looses 25% of their attack and def for X turns (I think 100 turns would be fair).
The user should also not be able to use jutsu's. Awakening the Bijuu would cost all of your chakra.
If you have a Bijuu you should not be able to get the Curse Seal or 7 star or Kekki Genkai.
I think this is fair, there are positives and negatives. And even if so you should need to use like 50 DK points to train for this (maybe more?)
I think the Kekki Genkai should also require a certain ammount of DK points devoted to training as well.