Could Midnighter defeat Swamp Thing ?
Swamp Thing is (if I recall correctly from the last time I looked it up) an Earth Elemental so among other things he's immortal so I don't think Dooring him anywhere would kill him, and I'm pretty sure he can cross dimensions so he'd be able to come back to the fight. And unless Midnighter's Dooring the whole area I don't think he'd get rid of him easily in the first place. Also, I didn't feel like bringing up Doors this time.
Once again I'll ask, why is death the only way to declare victory? I see no mention of a fight to the death, merely a simple question, "Could Midnighter defeat Swamp Thing?" Defeat, you know, that thing that can occur from a wide range of possibilities (besides death)
I'm going to have to disagree with you on that one. I don't believe Midnighter is ALWAYS going for the kill. He fought Grifter and wasn't trying to kill him, as well as Kyle Rayner.
As far as what else he could do, I already said using the Doors in a creative way. I know you said Swamp Thing could and would come back, but how long would it take? If Midnighter and Swamp Thing went at it, and Midnighter was able to affectively use the Doors to drop ST off in space, and it took a year for him to get back I would declare that a victory for Midnighter.
Of course he doesn't go for the kill when main characters are involved! If he killed Grifter the whole Grifter/Midnighter mini would have been shot to hell. Killing Kyle would have messed up the Search for Ray Palmer series. Compare those to all the rest of his appearances in The Authority and you'll see those are exceptions (because of plot) to the rule.
I don't know how fast he'll get back if he can, but why assume it will take a year if you have no info at all? The fight shouldn't be decided on possibilities based off of insufficient information.
I was just using a year as an example. It could take an hour, or 30 minutes, the point was Midnighter isn't going to stick around and wait for him. Removing an opponent from the ring is a victory in my book. As for the death thing. Even if Midnighter is going for the kill, his victory doesn't depend on it. The statement Zoom made was that Midnighter couldn't kill Swamp Thing, and there for he loses. Which isn't the case. Midnighter doesn't need to kill Swamp Thing to win (no where in this thread is it stated so) even if Midnighter was going for the kill, and performed a move in which he believed ST dead and left, is that not a victory? If he dropped him off in space and just assumed it killed him, is that not a victory?
I count BFRs as a win, but only when the enemy can't come back on their own. We don't know how long it would take for Swamp Thing to come back so why assume that it's going to take a while? What if it takes a couple seconds? With no information at all, isn't that just as likely? I'm opting for the situation that results in the fight being decided by things we know and not by things we don't.