Pokémon GO's first Battle League season has now shifted from the Great League to the Ultra League for the first time. Here's what that means.

Niantic hasn't let the ongoing global pandemic dampen the launch of its Pokémon GO's Battle League. Its first season is currently underway and for the past two weeks, trainers have been able to compete in the Great League portion of the ranking system. This past weekend, the difficulty was upped as the season shifted to Ultra League for the first time.

Season one's Ultra League will run from now until April 10, 2020, at which point it will switch to the Master League. To qualify for use in the Ultra League, Pokémon must have a CP between 1500 and 2500. This will make things considerably more challenging for trainers, and may even render some ineligible.

The most frustrated trainers will be those who missed out on catching Rufflet during the Great League portion of season one. Niantic switched the Pokémon's debut to an earned encounter during Battle League from the originally planned Safari Zone appearance, given the global circumstances. Trainers will have other chances to catch Rufflet in the future, but there's currently no knowing when that second chance will come.

NEXT: Pokémon GO: The Best Teams For Ultra League