Ratchet & Clank

Use the "<triangle> double-tap" technique to switch between the Holo-Guise and the weapon you want to use. Wear the Holo-Guise and then select the weapon you want to use. Now double-tap <triangle> to switch back to the Holo-Guise. Test it a few times so you can swiftly switch between the Holo-Guise and the weapon and then back to the Holo-Guise.

Use the Taunter when the Sentry-Bots have gone into their rooms to lure the Robo-Dogs into the barrier to get rid of most of them while you can stay behind the barrier. Hop over the barrier and back to lure the rest of the Robo-Dogs nearer to you so you can also lure them into the barrier with the Taunter.

When the Robo-Dogs are all gone you can safely hop over the barrier and switch back to the Holo-Guise. I would advise using the Walloper on the Sentry-Bots, as it kills them with one wallop. Follow each one into its room and wait until it turns its back on you. Double tap <triangle> to switch from Holo-Guise to Walloper and get rid of the Sentry-Bot before it opens the door. Switch back to the Holo-Guise before you open the door. Repeat for the other three Sentry-Bots.

Try Zoopsoul's FAQ. His level in the FAQ is 12.0. He provides a lot of answers.