I would have agreed with the last poster, until looking this up on the Web. It seems that more than one University syllabus groups transformers with other electric machines (such as generators and motors and indeed motor/generator combinations, which might be where they see the commonality). Could this be a light-current versus heavy current thing - maybe the power guys have always classified transformers that way?
If the original poster attends one of these institutions, he/she might get more credit for describing the common points between a transformer and other electrical machines, than arguing semantics with the teachers. After all, I suppose you could regard a transformer as having something in common with a lever or a gearbox. Similar rules apply, in that you can trade voltage for current (compared to force versus velocity), but their product can only be the same at most, actually always less due to losses.