Gorosaurus and his awesome performance during the battle. He was the only monster who managed to bring King Ghidorah onto his belly, and he did it twice: the first time by pulling on Ghidorah's left head (after charging through a salvo of gravity beams), the second time by kangaroo-kicking Ghidorah in the back while Godzilla and Anguirus are dealing with the outer heads.
Well, almost everyone. Aside from those who did not make an appearance, Varan and Baragon don't do anything. Justified since their suits were in pretty terrible condition at the time. Still, that doesn't make the fight any less better.
Usually it's just one or two kaiju attacking Tokyo, this time it is Godzilla, Mothra, Rodan and Manda getting a spotlight during the epic rampage.