Gengar is a dual-type Ghost/Poison Pokémon. Gengar evolves from Haunter after being traded, and is the final form of Gastly. Gengar can further mega evolve with Gengarite, which can be purchased from the BP Store in the Battle Colosseum for 200 BP.
Mega Gengar Edit
Upon Mega Evolution, Mega Gengar gains the ability Shadow Tag.
This prevents opposing Pokèmon (that are not Ghost types) from switching out. But at the risk of mega evolving may cause the old ability Levitate to stop working and he will be vulnerable to Ground moves, so play smart with his Mega Evolution.