Smith, even if he can't absorb Ultron, Ultron was a pussy in AOU and Smith was basically the top dog where he's from, Neo had to outsmart him to beat him
neo defeated Oracle smith because he knew that if one couldn't exist then neither could the other. Neo was the ONE and Smith was THE MANY. the whole binary opposite speel
if this include oracle smith then oracle smith had reality warping powers, if not then smith still wins as he can copy himself over to any one or program within the matrix as a back up. being "unplugged" smith is now stronger and almost on par to "reborn" neo.
not only that if neo hadn't stopped smith then the smith program would have taken over the machines which was stomping zion, not only that smith would have sent other machine counterparts to purge zion.
smith had means to access the machine world and if he had that then ultron would be screwed because we only see ONE machine city. the cities are global, like the fields of matrix inhabitors who havent been "jacked"