It's the first day of October, so what better way to start the month than a spooooky new Wi-Fi distribution for Pokémon X and Y! That's right, from now until Halloween (October 31st), you can snag a special Super-Size Pumpkaboo from Mystery Gift over Wi-Fi!
This Pumpkaboo is the largest of the four sizes of Pumpkaboo available, Super-Size, and as such has the highest HP of the sizes. Not only that, but it is equipped with haunting moves such as Trick-or-Treat as well as Scary Face. If that weren't enough, the Pumpkaboo received from Mystery Gift wears a Rocky Helmet to inflict damage on foes that damage it with a direct attack.
Since you'll need to have a Super-Size Gourgeist in order to participate in the Trick-or-Treat Friendly online competition, all you'll need to do is trade your Super-Size Pumpkaboo to another version in order for it to evolve into Gourgeist. Only Ghost-type Pokémon are able to participate in this single battle tournament, although both Rotom and Giratina cannot participate.