I don't see this being a good matchup, especially against hybrid builds running Palkia G. He can threaten Lost Cyclone, threaten damage (not GREAT damage, but damage) to make you sacrifice, while putting Gengar back in front of your Regigigas to punish your sacs. Without any trainer lock he can set up quickly, as well - if he gets a T1 gar, you might as well scoop.