Basically it allows for Mega Blastoise to punish mons that try to punish or prevent a spin, allowing you to spin easier. Could be nice with like Volcarona to weaken a lot of the walls that can eat a hit or two while still removing hazards.
Of course does leave it a little lacking damage wise against opposing waters, with Slowbro in particular coming to mind, so maybe something like AV Tangrowth or Raikou to handle those would be solid.