Battle Royale, Kaiju style!!

If Lore is something that can be reliable to go on. Godzilla would win hands down. As the amount of RADIATION the big lizard gives off would FRY everyone and his breath weapon would add to it.

That is just saying if some Lore is followed. Godzilla's Lore is always messed with.

The Colossal Titan just sort of looks like he's there to just try to break up the fight.

You know what's funny about this image?

It's that Godzilla would stand twice as tall as the Colossal Titan.