From Bulbanews, your community Pokémon newspaper.
To be distributed throughout October
A Super-Size Pumpkaboo will be distributed via Nintendo Network from Oct. 1 to 31. It is holding a Rocky Helmet, is in a Cherish Ball, has a random nature, and has the moves Trick-or-Treat, Astonish, Scary Face and Shadow Sneak. It can be either male or female, and can have any of Pumpkaboo's possible Abilities (including its Hidden Ability). It will be available for both American region and PAL region games.
It is being distributed to promote the Trick-or-Treat Friendly (which had been tentatively titled the Halloween Party in English until today). In the friendly, all players must have a Super-Size Gourgeist on their team, so this Pumpkaboo will make it easier to obtain. Pumpkaboo come in four sizes, and Super-Size is the least common.