The game was recently launched in my country and all gyms close by are occupied by level 20+ trainers with cp 2000+ rare pokémons.
A quick search revealed other players in my country complaining about the same thing and a link to report players (https://support.pokemongo.nianticlabs.com/hc/en-us/requests/new?ticket_form_id=319948).
How do I know if the player is indeed cheating or just played the game too much? Is 2000+ CP possible to achieve without cheating? And what information I should include in my report to Niantic?