I am trying to do so service to get some achievement/trophies for certain trains. If I created a Scenario with Scenario Planner does it count as a service? Please and thank you
No, it counts as a scenario. I can definitely say it doesn't count as a service towards an achievement like "Complete 100 services on route X". NOTE: the quickest way to unlock such an achievement is to do a service from the timetable, and save just before the end (before coming to a complete stop at the end, or before the doors close on a passenger service), and then reload that save over and over. The closer to the end you save, the quicker it will be to loop.