Darth Yoda vs DE Sidious

Dooku has confirmed that Prequel era Sidious would get annihilated by Darth Yoda:

"So be angry about that!" Dooku said. "Hate! Rage! Despair! Allow yourself, just once, to stop playing at the game of Jedi Knight, and admit to what you have always known; you are alone, and you are great, and when world strikes you it is better to strike back than to turn your cheek. Feel, Yoda! I can feel the darkness rising in you. Here, in this place, be honest for once and feel the truth about yourself."


At this moment Yoda turned, and Dooku gasped. Whether it was the play of the holomonitors, beaming their views of bleak space and distance battles, or some other trick of the light, Yoda's face was deeply hidden in the shadows, mottled black and blue, so that for one terrible instant he looked exactly like Darth Sidious. Or rather, it was Yoda as he might have been, or could yet become: a Yoda gone rotten, a Yoda whose awesome power had been utterly unleashed by the power of the Dark Side. In a flash Dooku saw how foolish he had been, trying to urge the old Master to the Dark Side. If Yoda ever turned that way, Sidious himself would be annihilated. The Universe had yet to compehend the kind of evil that a Jedi Knight of nearly nine hundred years could wield." -- Yoda: Dark Rendezvous.

How does DE Sidious fare against Darth Yoda?

Still think Sheev would win but it's hard to say.

Well would this Yoda just become DS or would he get those nine hundred years to study and train in the darkside?

Still entirely possible that Dooku was overestimating Yoda. 

Leaning Sheev.

Yoda wins

leaning sheev by the fact he have actual feats that this what if version of yoda