The X-Strike is a special technique performed by Scott Pilgrim and Ramona Flowers in Scott Pilgrim's Finest Hour. The move is performed when Scott and Ramona gain the Power of Understanding and the Power of Love respectively. The attack is used to defeat Gideon Graves once and for all in the final battle inside the Chaos Theatre.
The move is executed by Scott and Ramona dashing towards Gideon and striking him with their swords, forming and "X" shape on the floor. The Technique is powerful enough to rip Gideon to shreds, defeating him and turning him into coins.
The X-Strike is a special ability known as a "Double Tech" in the 1995 RPG, Chrono Trigger released for the SNES. The move is performed by protagonists Crono and Frog and is performed in the exact same way it's performed in the Scott Pilgrim series. The move also appears in the game's sequel Chrono Cross but is performed by characters Serge and Glenn.