Ahh it seems you dont need to get 440 Riddler Challenges to confront him. Must be about 400 because ive still got some left to find and Oracle gave me his location. On my way now to finally get the bastard.
The Riddler Challenges in this game are so much better than the first because you have a goal and also because some of the Trophies in the cages are alot of fun to try and figure out, rather than jsut finding them lying on the ground.