Aguero does build some of his attacks from deep left but roams a lot. And width is usually provided by one of Kolarov/Clichy or Nasri/Milner. How Villa plays for us, is entirely diff to Aguero's role for city.
Well in theory it SHOULD be that but it has not always occured in practise. Neither Agüero, nor Villa or Henry for that matter are natural fits when it comes to that position.
Aléxis is a MUCH better fit as well as Neymar.
But at the end of the day I would not rule Agüero out at all. Sure he is not a regular winger but who has claimed that? As a matter of fact we have not used regular wingers since the days of Overmars etc. Could Agüero play a similar role to that Villa and Henry had? Yes why not?
Nobody says that they should play in the exact same manner. When you have an atttacking force made up by Messi, Aléxis and Agüero they are bound to create fluidity. And as we all know Pep is not the type of coach that sticks with the one and same lineup/playing style.