Rodan (ラドン, 'Radon') is a giant pteranodon introduced in the 1956 Toho film Rodan. Rodan is a big buddy of Godzilla. He fought Godzilla in Final Wars alongside Anguirus and King Caesar. Godzilla spares them but in a deleted scene, Godzilla kills them. When Rodan and Godzilla were fighting Mecha-Godzilla 2, Rodan gave it's life force to Godzilla to revive him. So he is without a doubt, a great ally.
Rodan appears with Mothra Leo, Anguirus, Mothra, King Caesar and Baragon a few moments after Godzilla joins the Heroes some of them do not trust the heroes at first, and have to be defeated by the monsters that trust the Heroes, most noticeably, Godzilla. Rodan does not trust the heroes, so he must be convinced.