Had he not appeared in Ghidorah, the Three-Headed Monster, which established them as friends, Godzilla vs. Rodan may have happened at some point down the line. Due to Rodan's flying ability ...
As for the Monsterverse version, Rodan hasn’t teamed up with Godzilla yet, but the door is open for that to change at some point down the road. Bowing down to Godzilla in Godzilla: King of the ...