[Kazo]

Not sure if this has been said yet, but I am like 99% sure that you can only have 1 merged Kyurem at a time. When you use the item to merge Kyurem, it becomes a different item(still called the same thing/same icon) but this item will only separate Kyurem. It wont let you merge another set until you separate the merged Kyurem. It then turns back into the original item.

This means it is illegal to use both of Kyurem's forms on the same team.