For 1 the Akatsuki leader has the ability to use the Shapeshifting Technique . This technique creates a duplicate of a person using another body. This duplicate's abilities are proportionate to, and limited by, the amount of chakra given to it by the duplicated person. This jutsu can't be seen through by the Sharingan or Byakugan. It seems to be unable to duplicate kekkei genkai, though this may be because of a chakra limitation. It is precise enough, however, to allow the copy to reproduce most of the jutsu of the original, minus those abilities requiring kekkei genkai or other special traits. The duplicates can either be controlled autonomously, or be controlled by the originals. Once the chakra runs out and the sacrificial body dies, the Shapeshifting Technique will end and the lifeless body used will be revealed.
So maybe if their hideout possible may have to get through his minions in which he uses this jutsu like for example he creates the 1st Hokage , but its only a Duplicate not being as strong , but it was an example of cource.
Of cource could have the idea as the ulimate challenge was to face all of them 1 by 1 , but after beating one of them , must give up at least 500 gold or 10 gems to get fully healed , then face against other member, until reach the leader , but as you can think this challenge could be deadly , since before facing each Member go against a spy/minion which the The technique the Akatsuki leader leader uses makes a duplicate of the person may go against , but 3 times weaker , but he may be someone different.
The scary thought is the weakiest Akatsuki member be Orochimaru lvl , then it continues.
The reward could maybe count for 10 DK since be much harder to win , 100,000 gold , or 1000 gems. Not certain if Neji would accept it , but its an idea.
