he was going to be like a lizard... green... with no fur.... the ewoks were going to be wookies instead of teddy bears... he took a wookie instead at the ends... havent you seen the previzualsation skethches of a new hope.... go look for it and youll see the lizard. The one that didnt changed that much was R2...
Sidious wins hands down
The simple reason is that one aspect of the dark side is "cunning". Just look at how he has fooled and tricked everyone in all the series. That combined with his knowledge of the force would annihilate Yoda.
the only reason he got killed in the end was because of Annikins Unpredictability, which is a danger for everyone. Luke didn´t kill him Annikin did. He restored the Balance by not only slaughtering numerous Jedi but also the emperor.
Well someones gotta go for Sidious havn´t they, might as well be me.
If you can bullshit the jedi council, including Yoda himself, you could certainly defeat him. Besides, how would Palpatine's age reflect his sabre skills, Yoda is over 800 but through the force he does backflips and what not. Besides, Sith means warrior, Sidious will throw down some light sabre action that will easily match Yoda's speed.
However, his overconfidence will lead him to believe he destroyed Yoda while Yoda will escape.