He's still only battling three monsters in DESTROY ALL MONSTERS; Godzilla, Gorosaurus, and Anguirus. Minya, Mothra, and Kumonga don't intervene until Ghidorah is basically already down and out. Rodan takes off at the start of the battle, and Manda, Baragon, and Varan are nowhere to be seen.
I still don't think King Ghidorah really got his "ass kicked" in MONSTER ZERO. It seems that Godzilla and Rodan just simply annoy the shit out of him, and he can only really take so much.