Perhaps you can help by uploading a picture of Unison Rush being use in-game.
Unison Rush (ユニオンラッシュ Yunion Rasshu?, lit. "Union Rush") is a technique in the international and Final Mix release of Kingdom Hearts Birth by Sleep. It involves all three players rushing around the field and attacking enemies with their Keyblades, prompting them to press the button on-screen for maximum damage, similar to a type of Shotlock. It is most effective during Mirage Arena battles.
In Kingdom Hearts Birth by Sleep, Unison Rush is an Advanced Friendship Command that takes up three slots in the Command Deck, has a maximum level of 1, and a normal reload time of 50 seconds.