How many existing challenges are there and for what tailed beasts? There be a comprehensive list of that before they can be awarded or revoked? Also, I'd like to say that i haven't posted a challenge yet but i would like to put my name in for SHUKAKU!
And i super agree with the guidelines posted by Chinote so far!
Just one more point, i think that the previous relationships formed between tailed beasts and their Jinchuriki should be wiped clean including claims of "remaining chakra from extraction." Also, i think that if a tailed beast is to be extracted from a host the host should die point blank, character death no exceptions. This will make the gravity of challenges and the following battles way more serious