Chapter 3: Arkham Asylum Antics
Head to the right and destroy the two glass tubes to stop the fountain. Assemble the pieces then use the grappling hook to drain the water and unlock Robin's Acrobat Suit. Place his stick on the hole in the wall, then double jump to reach it and jump to the other side. Continue around the path and defeat the goons. Grab the handle to topple the statue's hat. Assemble the pieces to unlock Batman's Power Suit. Double jump again to reach the wall with the jumping lego pieces to create grappling handles for Batman.
Switch to Batman and cross the gap. Change to his Power Suit then destroy the silver wall to the upper right. Climb the wall then destroy the silver statue to topple it and destroy Catwoman's bike. Follow the path then continue to the left to find a silver winged statue. Destroy it then reassemble it.
Switch to Robin and use his bubble ability. Jump on the mechanism and use to move the bat logo to the far end of the wall. This will unlock Batman's Bat Suit. Go to the right and use the Bat Suit's Sonic Gun to shatter the glass pieces. This will take care of Two-Face's truck. Backtrack to the left a bit then go down then left again to find a glass wall. Shatter it to find a mini-kit.
Head to the right then down to encounter Bane's Mole Machine. Go back to the left first then switch back to your Power Suit. Take the lower left path and follow it to find a silver statue. Blow it then use the ramp or just follow the hallway to find two grappling handles. Both characters must pull it down to activate it.
This will unlock Robin's Ice Suit. Change to that and use it to freeze the gushing water from the silver statue you destroyed earlier. This will stop the mole machine and complete the level. Talk to the commissioner to start the next chapter.