To defeat Costume Gengar, going in with the team you created for the Mega Gengar Raids based on our counters guide will be perfectly fine. However, there are small tweaks you can make to your team to specialize it to Gengar’s Tier Three level. For this lower level raid, regular Mewtwo with Confusion and Psystrike take over from Mega Gengar as the top non-Shadow counter. This means that it won’t make a huge difference if you have a Mega Gengar on your team, so if you’re not going to do a bunch of raids in the next eight hours of Pokémon GO gameplay, skip out on the Mega Evolution for the time being. Replacing Shadow Tyranitar as a top counter are Shadow Metagross with double Psychic-type moves and Shadow Weavile with double Dark-type moves. Other sure bets are: