Take out your cryptographic sequencer and hold L1 and R2. Rotate the right analog clockwise. Do this until Batmans head becomes big. All enemies will have a big head as well.
Easy way to get the Flawless Freeflow Fighter 2.0 trophy
Go to the Riddlers Challenges and go to Custom Challenge. Select the first map and under modifiers choose Takedown Projectiles. This will make it so that your batarang will knockout enemies in 1 hit. Spam the batarang through all 4 rounds knocking out the enemies without getting hit once and you will get the trophy.
Hidden Message
Use Batman's Cryptographic Sequencer and track down the XY coordinates 700, 490. You'll intercept a radio frequency that reads the following numbers: 9-23-9-12-12-18-5-20-21-18-14-2-1-20-13-1-14 (it will then make a buzz sound and repeat these numbers) When matched to the corresponding letters of the alphabet they spell out I WILL RETURN BATMAN.
New Game+
Beat the story mode on Normal or Hard difficulty.
Scarecrow Hideout
Go on top of a boat near the industrial district (the boat should be near two cranes). While on the boat, take out the cryptographic sequencer and use it. Letters will appear instead of the radio stations. Turn the letters until it reads "City Of Terror." A secret passage on the boat will open. Go down into the boat to find hundreds of roaches, a medical order form addressed to Jonathan Crane, and a Scarecrow victim who will squirm if you zoom in on him.
Taunt Animation
To make Batman (or any other playable character) execute a "taunt" like they do in the beginning of a challenge map or round, rotate the right analog stick clockwise two or three times. If you execute a taunt before performing a glide kick, the camera will change into the enemy's perspective during the glide kick action (only works for Batman or Robin).
Big Head Mode...