Well, an f4/GK deck w/ Cosmic Radiation sounds like a good idea actually even if your batman gets overloaded, you've got a Batgirl and Heavy Hitter who can become huge. w/ all the PTs and Pumps

Other then that, I prefer that GK decks stay with a boosted Azrael or Master of Magnetism, as a 5 drop Batman, 6 drop Azrael/Nightwing, and 7 Drop Magneto out at the same time is much better then a 6 Drop and uncertainty of a 7 Drop Batman.

~Tombster212