Space Godzilla is a giant monster full of power. With his skills there aren’t many who can defeat him. Of course Luffy isn’t just an ultimately powerful being. He’s gonna be the pirate king! Not even Space Godzilla can challenge this kind of power. Luffy has the Gum Gum Jet Pistol! Luffy wins.
DReager1.com 
Luffy would destroy that crystal piece of stuff with one punch, like he owned Bellamy
Luffy would take a solid win, but Space Godzilla is definitely pretty cool
Took the dumb human characters and G 40 minutes to kill this one, Luffy could go G2 or G3 and kill him in 5-9 minutes. Heh, I’ll be puzzled if SG could even take hits from Nightmare Luffy.
Luffy would definitely defeat him in around 5 minutes, but Space G is definitely a force to be reckoned with. Luffy’s just too powerful