I know not everyone out there likes to go for all the achievements especially the really difficult ones, but I love getting them (if I really love the game). Perfect Freeflow was a challenge in the Arkham Asylumn I spend the better part of a week practicing my approach to get this achievement. I would miss it by forgetting a move, or try to pull off a move just to check it off my list when I shouldn't have used in that situation. But one I got it i found myself just sailing through all the beat down challenges, and hard mode was a lot easier. By trying to get this achievement I was able to train myself how and when to use each move Batman has available and I became a significant better player.
I am going to be practicing for this before going for the replay game+ mode so I can tear it up.
Here is a list of all the moves for those interested
Ultra Stub (B, B, B)
Aerial Attack (B, A A)
Beat Down (B, X many times)
Ground takedown (RT + Y)
Special Takedown (Y +B)
Special Batswarm (X + A)
Special Multi takedwon (Y + A)
Special Disarm and Destroy (Y + A) [i think you have to destroy a weapon for it to count]
Batclaw Slam (LT + Y, X)