Instructions
Activate your Sharingan. You need at least two bars of chakra to do this. The controls for activating Sharingan vary depending on which controller you are using. For example, if you are using just the Wiimote, you press back on the directional pad and the "1" and "2" buttons down simultaneously. For the GameCube or Classic Controller, you press back with the thumbstick and press "X."
Build up your chakra by attacking. You need a full chakra meter to launch Kakashi's secret technique.
Press and hold down the jutsu button when your chakra meter is full. As long as Deidara is in front of you, the technique will work. If you are using just the Wiimote, press "1" and "2" together; if using the GameCube or Classic Controller, press "X"; if using the Wiimote and Nunchuk, press "Down" on the directional pad. Your chakra will quickly deplete and Kakashi will use his secret technique.