Select Pokémon in Pokémon Go will now have the chance to grow stronger beyond their final form and gain access to their Mega Evolution. Traditionally in Pokémon, a Mega Evolution is only available in battle. But in Pokémon Go, you can Mega Evolve your Pokémon, and it can travel with you. You can take it with you on raids or fight it against Team Rocket. Will you be able to take it with you to use in the battle league?
When Mega Evolved Pokemon become available on Pokemon Go, players will not be banned from using them in the Battle League. Niantic hasn't said when they plan to introduce these powerful Pokémon to the PvP portion of the mobile game. Still, players needn't worry about battling a Mega Evolved Charizard X or Y anytime soon. Chances are that when you can use them in the Battle League, they will have a Battle League Class exclusively available for trainers to use.
For example, in the second season of Fight League, Niantic created the Premier Cup. It comes alongside the Master League, which allows trainers to use any Pokemon in their roster, whether it's a Mythical Pokemon or its max CP stat. However, the Premier Cup follows these same rules, except for the fact about Mythical Pokemon. They are prohibited. A similar system will likely be available for Mega Evolved Pokémon, allowing all Pokémon Go Trainers to participate in the Battle League, regardless of what Pokémon they have.
The Mega Evolved Pokémon is a concept that could introduce other alternate forms of Pokémon, such as Dynamaxing, released for Pokémon Sword and Shield. We already have Galar Pokémon in the game, but even these Pokémon are available in small waves.
