Odin wins if the fight happens in DC. Odin wiping out all plant life on earth has to count as a KO. It's a draw on Marvel Earth though. Odin's not going to mess with Gaea.
Let's say Odin does wipe out Earth's plant life and Swamp Thing shows up on another planet. What's to stop Odin from locating Swamp Thing again and wiping out that planet's plant life temporarily and so on. Sure Odin would make some enemies from alien heroes and Pantheons but he could still do it.
That's like trying to wipe out all bacteria.. There's flora in places you wouldn't think of, like in the intestines. Swamp Things been known to mutate them into massive plant forms.
Odin wins both. What can ST do to him? Don't tell me that "Gods" have plant life in their intestines that can be manipulated. If that's the case, let's try a Gardener with the time gem vs Odin.
But that's not all he can do.. If you've read Alan Moore's run on swamp thing alone, you'd know he's pretty powerful in general, and powerful in a swamp in particular.
And Mark Millar takes what Moore did and basically exaggerates it.
Yeah, I've read Moore's ST. After Millar, it's been sort of left up in the air where he stands, power wise. That's why I'm choosing Odin. And I don't know if Odin has to eat, but if that's relevant, I can start an Odin vs. Salmonella thread. I'm assuming Odin would win.
We need a defined battle field when it comes to Swamp Thing. If they leave the swamp it should be considered self bfr, hence Odin can just kill all the plant life in the place and ST loses.
Thanos and his clones do alot of things. So Jimmy Olsen+Odin's favorite jelly donut+Syrup of Ipecac=win for Jimmy! I think it's safe to say that Odin and his gut are not allegorical to a seagull being fed Alka-Seltzer. I just don't buy that his GI tract is his kryptonite.