I believe Kyurem, when running moves like Substitute, Roost, Freeze-Dry, and Earth Power, should be banned, as it can be extremely frustrating to face. This set allows Kyurem to continuously set up Substitutes, heal with Roost, and deal massive damage with Freeze-Dry and Earth Power, making it hard to counter. It can quickly become overbearing and difficult to handle, which can negatively impact the metagame.