Game:Master Control Program

Attack the walls surrounding him and use the Reaction Command. This is the only way to defeat him. You must have Tron in your party.

Since reaction commands technically count as hits this is a great way to level up Valor form.

Sark does all the attacking. During the battle with the MCP, Sark again throws his disk (which has proportionately increased in size) and shocks the ground when Sora is close. He also raises a wall, which allows Sora to again use the Reaction command, instantly destroying the head. Sark's two feet must be damaged to make him kneel, so his head can be attacked - destroying the head stuns Sark for some time, but he will be regenerated by the MCP.