Rodan and Kumonga would win this match if they cooperate well together as a team. Ghidorah is the only monster with a beam weapon and Mach 3 flight, so those attributes can be used against the duo. Ghidorah's superior speed would impair that of Rodan's, but it could be slowed down my Kumonga's web. Rodan alsohas the strength and durability to ram into Ghidorah and knock him down to the floor. On ground, Ghidorah would be assualted by Kumonga, who would have no problem dishing out pain. While Kumonga does this, Rodan could pin him to the ground by patrolling the air. In the end, the duo have a good chance of winning.
Kumonga and Rodan: 8/10
King Ghidorah: 2/10