Today marks the start of the long-awaited (at least for some) player-vs-player mode in Pokémon Go. In a new blog post, Niantic announced that the Go Battle League will start rolling out today, with high-level players being the first to get access to the new feature.

According to Niantic, Go Battle League is officially in its preseason, with actual ranked seasons coming later, presumably once the League is available to everyone. Niantic will be using the preseason to tweak Go Battle League’s balance, fine-tune the threshold for gaining ranks, and determine the best length for seasons, so players who get in early can expect some changes once ranked play really starts. However, it also means that any ranks gained during the preseason will be “partially reset” when Season 1 starts.

That doesn’t mean that there’s no reason to play in the preseason if you’ve been invited, though. Players who gain ranks during this period will still earn some decent rewards. Players in Go Battle League can unlock sets of five online matches at a time, and at the end of those matches, they’ll be rewarded with Stardust based on how many they win. The more matches they win, the more they’ll increase their rank, which can grant additional Stardust.

Other rewards include battle items like Rare Candies and TMs, and “exclusive Pokémon encounters.” The first such encounter is Pikachu Libre, a Pikachu with a wrestling outfit who can only be found in Pokémon Go as part of Go Battle League. League players can also earn avatar items based on the electric-type luchador.

Go Battle League will rotate through three different leagues in each season, including the preseason, but trainers will keep their rank even as leagues switch. The preseason will start with the Great League today before moving on to Ultra League on Feb. 10, Master League on Feb. 24, then back to Great League on March 9.

Niantic still hasn’t announced when the preseason will end and Season 1 will officially kick-off.