If you want for the lamest way then just A Skewer merciless and get ready for 2A if they close you in.. The Al is extremely terrible against zoning. It tires your fingers and mind, so be sure to take a break for some minutes.
Trust me, i got 20 wins with Waldstein by just throwing boulders.
If you encounter Yuzuriha or Hilda between 20-30 just be careful not to exaggerate with Skewer since they sometimes teleport behind you and try so hard to hit you with Infinite.
This is why the leaderboards is filled with Hilda lol