To get this weapon you'll need a sword that can break walls. In the Garden Hall (Present), starting from the middle passageway at the very top of the hall, do a wall run to the rope, then a wall run to the central platform. Turn left and walk directly through the wall of rubble in front of you. You'll turn around and grab the platform you were just standing on. From here, jump across the gap to the next platform. To your left you'll see another platform with a switch. Make your way there, hit the switch, then return to the platform you were just on. There will now be a block you can climb on. From the top of the block, do a vertical wall run + jump to reach the beam above you. Walk along the beam to the right, then jump to the ledge on the far wall. Follow the ledge around to an alcove. Drop into the alcove and break the rear wall on the right-hand side to expose a weapon rack. Break the rack and you'll be able to pick up the Pink Flamingo, an unbreakable secondary weapon that does moderate damage and knocks all regular enemies to the ground with one hit.