It was not wearing a rocky helmet. It might have been holding onto that berry that inflicts damage to the enemy when the holder is damaged? The one that starts with a J. But that berry didn't activate while I was playing.
Yes, they used one move, and then they used it again, infinitely, until my Furret fainted. It happened on multiple different occasions during a turn I went to use confusion. But it also happened with other moves at least once.