Rakuhouha

Rakuhouha ("Fallen Phoenix Crush") is the technique Zero learns from defeating Cyber Peacock. And this is Zero's Giga Crush (X has a Nova Strike from the secret "Ultimate Armor"), so you press the "Giga Crush" button (instruction manual usually tells you) to send out several energy shots at once. This is the only technique of Zero's that has weapon energy, and it recharges from weapon capsules or from being hit (as is usually how Giga Crush is restored).