I'm assuming you mean 8 and 9, none of the 10 or 'special' bosses are testable yet.
However you have to remember that these are basically the rank 6 and 7 bosses of last tier, they aren't supposed to be as difficult as the rank 10 ones.
These fights are a monstrous improvement in mechanics versus the old 1-8, Ahroo'u will prove to be a huge challenge for anyone that can get to him.