I killed the ''expert cat'' with water main, haku, suigetsu and gnw tenten... A steady combo and poison did the rest :)... with my normal team i couldn't kill him so, my suggestion is to use ninjas that buff your team like you do with the fox and don't use control skills as you should be able to tank his attacks :)
Sorry, but did you use normal Haku or Edo Tensei Haku?