Oonoki has the problem of hitting A due to A's speed. Tsunade defeats Mei. If A blitzes Oonoki before Oonoki gets of the ground he's screwed. To be honest I'd call it a tie. They both kill each other.
onoki flies up with mei on his back and jintons the battlefield. alternatively he makes an army of rock clone and pins A down so he can make him weigh several tons, THEN disintegrate him.
A only speedblitzes if the starting distance is close enough