This Ghost/Poison-type Pokemon is made up several toxic gases--touching it would be really unpleasant. Instead, try to take it out with projectiles. It's not the fastest enemy in Smash Run, but occasionally it may try to chase down a fighter, so be careful around this gaseous foe.
Gastly is a First-Gen Ghost/Poison type Pokémon that first appeared in the Pokémon Red, Blue & Green games. It evolves into Haunter at level 25, and then into Gengar through link trade. Its Pokédex number is #092.