Man Thing vs. Mr Sinister

fight takes place on neutral ground

Who wins

Can Sinister use a controlled burn like re-entry of the space shuttle of the Phoenix?
He might be able to re-create a new phoenix in this fight.

Yes

Phoenix would be useless against Man-Thing.

As long as Sinister keeps him at a distance and uses his TK/energy blasts, he should be able to put Man-Thing down. But if Man-Thing touches him, he's dead.

His fear touch/death touch is extremely powerful.

Mr. Sinister would have to leave his body to defeat Man Thing.
A lot of telepaths can do that even though the Professor can't.
If Mr. Sinister let Man Thing assume control of his body he could snatch all the tones that Man Thing can teleport to makeing beautiful Sinister music out of it.
In effect he would assume control of Man Thing's locations and could concievably drive him crazy through teleportation like Jeff Goldbloom went a little off the wall in The Fly.