I know I'm really late to the party, but in response to all the talk about Regigigas+ball, I'd say Net is the best. The Great ball matches mostly on the physical properties, but the Net animation matches flavor-wise. When you're caught in a net, you can't move as fast (or at all) or maneuver very well. We know Regigigas' ability, and I think that matches flavor-wise (and takes 5 turns to remove the net).