Megaman can use Ken's Shoryuken if you get all of the energy tanks, all of the hearts, and all of X's parts. The capsule for the shoryuken is in the third x-hunter stage (Agile). At one point in his stage, there is a ladder with many bats around. Use the Crystal Hunter to crystalize a bat to reach the ladder. Follow the path until you reach a downward path. Scroll on the left side of the path until X discovers a passage. You must be at full power for the capsule to appear. Dr. Light will give you Ken's Shoryuken.