Well after taking a break from Batman Arkham Asylum, I went back to try and get the rest of the achivements for the Platinum Trophy. All I was missing for the Platinum Trophy was

Biggest Bang: Silver
Deliver an explosive knock out blow to the Joker (Hard difficulty) 

Freeflow Gold: Silver
Achieve 24 medals on combat challenges

Perfect Knight: Gold
100% Complete

Since all I needed was Freeflow Gold to get Perfect Knight, I saved beating the game on Hard Mode for last. Well I got both Freeflow Gold and Perfect Knight last night, so I went ahead and started the game again on hard mode to finish up the achievements. Well I just beat it and got the Platinum Trophy for Batman Arkham Asylum and it feels so good having completed everything. The best part about this game is the DLC that is being released for it. So far I believe two DLC map packs have been added to the game. I haven't tried them out yet, but from what I've heard they're pretty fun.