Raikage. Even as a Jinchuuriki, B admits that A is still stronger. Not only that, but A is the FASTEST shinobi alive in the manga. Only rivals now is Naruto. Minato doesn't count since he's dead. He also has a strong electric shield. It all comes down to Samehada. The funny thing is, Samehada is B's now. So does Kisame have Samehada or not? Without Samehada, A takes the battle medium difficulty. With Samehada, he still wins high difficulty.
bee never beat a serious A. when A got serious he bit chslapped bee like he was an annoying fly. kisame regenerated because he had already taken so much bee chakraBee in v1 beat As v2 laraite kisame took v2 bee