Simmons was a major doubt after suffering a leg injury in last weekend's 19-13 victory over the Highlanders, while Ioane missed out through pneumonia.
But both have been passed fit and will start the crucial clash against their fierce rivals, along with flanker Liam Gill, who also returns.
''I'm good to go," said Simmons.
The ice pack is my new best friend, unfortunately, but it's been working pretty well for me.
''It was very swollen just for a cork, which was a bit concerning, but we got scans … and since then, the swelling has reduced.''
But the Waratahs have not been so fortunate on the injury front and head coach Michael Foley has been forced to reshuffle his pack ahead of the clash.
With Wallaby No.8 Wycliff Palu ruled out, Sitaleki Timani starts with Dean Mumm moving into the back row.
''With Dean Mumm there, they still have a pretty good lineout and their scrum will be powerful - that's where we expect them to come at us,'' added Simmons.