who would win a a smaug without fire or shelob?

Smaug would eat Shelob then die from eating poisoned food.

Smaug no doubt. Could you actually trust that wyrm not to use its fire?

I think Smaug would defeat Shelob easily even without using his fire. He has a huge advantage in size and strength. Also, her stinger would have a difficult time penetrating Smaug's scales.