Power bricks can be found at the following locations:
You Can Bank On Batman Hidden on the left side of the cage that Clayface stands on.
An Icy Reception In the building behind the catwalk after you find the ice cream on the floor. You must glide to it from where you built the grappling grab spot. You will also need to do it in Free Play mode because you need someone who has super strength such as Clayface or Mr. Freeze.
Two-Face Chase The power brick is hidden in the final stage of the level where you fight Two-Face. It is in the top left corner of the park on the left and is behind some explosive barrels.
Riddler Makes A Withdrawal Build a car out of the pieces of the neon light on the side of one of the buildings after you come out of the elevator. Take the car to the area where you build the wrecking ball. In the top right corner is a car compacter. Roll the car in there then mind control the person to pull the second lever. Note - This must be done in Free Play mode.
On The Rocks In the first room after you come inside, freeze all of the ice cream floats and go across them. Do not mind control the person and raise the level. At the end of the floats is an iron gate. Blow it open and go inside. Go up the ladder and down to where the hanging bars are located. Break the crates, build the switch, cross the bridge, and complete the glass sculpture. Note - This must be done in Free Play mode.
Green Fingers In the room where you first use your power to grow plants, there is a ledge above the big plant thing. There are iron bars blocking the left passage of this ledge. Blow it open and use Robin in the Attract suit to build a truck with a cake in the back. Bake the cake and the brick will appear. Note - This must be done in Free Play mode.