Are you talking about the MCP? Use the reaction command when you're fighting Giant Sark by running away from him. Wall will come up, press triangle. Easiest way to defeat him is to have Donald in the party and use Fantasia or Flare Force on Sark to bring his HP down in both legs. Attack the moving walls and once a wall thing is gone, use Tron's reaction.
For the hostile program, basically have Donald and Tron in your party and use their reactions like Flare Force or Fantasia. Run around and get the dark orbs to fill up your meter. Once it's filled, Freeze him and bash it all you want until he unfreezes. For the lazer thing, you might need Aerial Dodge (Think that's what it's called. You use the square button) equipped on Sora so he'll get back on his feet in the air. Pack some items too. You basically repeat all that, when it flies around, get in the middle.