[Anaplasia] Janeway wouldn't, but I want to play "would Murf survive the threat" with the prompts

the Flood: nope, almost certainly not. they don't destroy, they infect, and he's an aquatic creature. the water would get him

the aging shadows: probably not. he does seem to age in some way, as evidenced by the metamorphosis, and he's matter that can break down

the spider-scorpion: now that's where he'd be fine. I doubt it could harm him at all

Zero would be fine against all of them, the biggest risk would be something destroying the containment suit and letting everyone else see them and go mad. score three for incorporeal beings