[quote=@Lucky]
Just curious, what's the period of time that this all takes place? One season?
[/quote]

Hard to say. Although the game does seem to have a day/night cycle outside of the wild area that progresses as you go through the game, and although there are a few points where you sleep in hotels and so on, if we took it seriously then the Gym Challenge would only last like a week, week and a half tops. Realistically it would be longer than that, I would think, to give people more time to beat every Gym; but then again, maybe the short time period is part of the challenge.

It definitely takes place over a set period though, with challengers requiring an invitation from someone from the league (including Gym leaders I would assume) to take part. They have an opening ceremony at the start and a Champions Cup at the end and only those who managed to get all eight badges in that time get to take part in the latter.