For those looking to mega evolve your Gengar in Pokémon Go, you’ll need to acquire enough energy to transform it. Unfortunately, the only way you’ll be obtaining Mega Gengar energy will be by completing specific field tasks or battling against Mega Gengar in the game.
Mega Gengar raids will be available from October 1 to 22. For those who have already been battling against Mega Gengar before this time, it’s a good opportunity to refresh your energy reserves and hold onto those for later. Like the Pokémon candy you receive for capturing and transferring a Pokémon, the mega energy does not contain a place for your inventory, so you don’t have to worry about making room for it.
There are also a handful of field research quests that you can receive by spinning Pokéstops. You’ll have to find these locations in-game and receive them in one of your three field research task slots. Of the two, the Mega Gengar raid battles are much easier to guarantee Mega Gengar energy, so long as you work together with a group. However, the field research tasks are easier to do by yourself, but the task you receive from a Pokéstop is random.
Mega Gengar will be available for a limited time. Mega Absol will be the next Pokémon to appear in mega raids starting on October 22.