What photos should I include in an ad of a bike?
Short version: As many as you can.

Slightly longer version:
I always include an overall photo from drive-train and non-drive-train side. In addition to that one of the cockpit and close ups of the drivetrain and brakes. That should include most parts of interest. In case of suspension photos of the sliding surface of fork and damper could be of intereset for potential buyers.